Ast liver enzyme normal range. Understanding Liver Enzyme Levels: When to Be Concerned and What They Mean

09.09.202310.06.2023 by alexxlab

What are the optimal levels of liver enzymes for males and females. How high is too high when it comes to liver enzyme levels. When should you be concerned about elevated liver enzymes. What do AST, ALT, and GGT levels indicate about liver health.

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Decoding Liver Enzyme Tests: AST, ALT, and GGT

Liver enzyme tests are crucial indicators of liver health. The three primary enzymes routinely measured are:

AST (Aspartate Aminotransferase)
ALT (Alanine Aminotransferase)
GGT (Gamma-Glutamyl Transferase)

These enzymes are predominantly found in liver cells but can also be present in other tissues. When liver cells are damaged, these enzymes leak into the bloodstream, causing elevated levels in blood tests.

What do these liver enzymes indicate?

AST and ALT are indicators of liver cell damage, while GGT is more specific to the biliary system. Elevated levels of these enzymes can suggest various liver conditions, from mild inflammation to severe liver disease.

Interpreting Liver Enzyme Test Results: Normal vs. Elevated Levels

Understanding your liver enzyme test results is crucial for assessing liver health. While reference ranges may vary slightly between laboratories, generally accepted ranges are:

AST: 10-40 units per liter
ALT: 7-56 units per liter

However, it’s important to note that these reference ranges may not necessarily reflect optimal liver health.

How are elevated liver enzymes classified?

Liver enzyme elevations are typically categorized as follows:

Mild: 1-2 times the upper limit of normal
Moderate: 2-3 times the upper limit of normal
Severe: Levels in the thousands

But what about values that fall just above the normal range or at the upper end of normal? Should these be a cause for concern?

Optimal Liver Enzyme Levels: A New Perspective

Recent research suggests that the traditional reference ranges for liver enzymes may be too broad and may not accurately reflect optimal liver health. A more nuanced approach considers gender differences and aims for truly healthy levels rather than just “normal” levels.

What are the optimal liver enzyme levels for males and females?

According to emerging research, optimal levels for ALT are:

Males: 29-33 units per liter
Females: 19-25 units per liter

For AST and GGT, a general guideline of 25 units per liter or below is considered optimal for both males and females. These lower thresholds can help identify potential liver issues earlier, allowing for timely intervention and prevention of more serious liver conditions.

When Should You Be Concerned About Liver Enzyme Levels?

While a single elevated test result isn’t necessarily cause for alarm, consistent elevations above the optimal ranges should prompt further investigation. Here are some guidelines to consider:

Transient elevations: A one-time result above 25 units per liter is generally not concerning.
Consistent elevations: Multiple test results above 25 units per liter warrant further investigation.
Moderate elevations: Levels consistently in the 50s or above should be evaluated more thoroughly.
Severe elevations: Levels in the hundreds or thousands require immediate medical attention.

Why are lower thresholds important for liver health?

Traditional reference ranges are often based on population averages, which may include individuals with undiagnosed liver conditions. By setting lower thresholds for optimal liver health, we can potentially identify and address liver issues earlier, preventing progression to more serious conditions.

Factors Influencing Liver Enzyme Levels

Various factors can affect liver enzyme levels, and it’s essential to consider these when interpreting test results:

Alcohol consumption
Medications
Obesity
Viral hepatitis
Autoimmune conditions
Genetic factors

Can lifestyle factors impact liver enzyme levels?

Yes, lifestyle factors can significantly influence liver enzyme levels. Regular exercise, maintaining a healthy weight, limiting alcohol consumption, and following a balanced diet can all contribute to healthier liver enzyme levels. Conversely, sedentary lifestyles, excessive alcohol intake, and poor dietary habits can lead to elevated liver enzymes.

Additional Tests for Liver Health Assessment

While AST, ALT, and GGT are valuable indicators of liver health, they don’t provide a complete picture. Additional tests that may be recommended for a comprehensive liver health assessment include:

Albumin
Bilirubin
Prothrombin time
Alkaline phosphatase
Hepatitis virus tests
Liver ultrasound or imaging studies

When are additional liver tests necessary?

Additional liver tests may be recommended when liver enzyme levels are consistently elevated, when there are symptoms of liver disease, or when there are risk factors present such as a history of alcohol abuse, obesity, or exposure to hepatitis viruses. These tests can help identify the underlying cause of liver enzyme elevations and guide appropriate treatment.

Managing Elevated Liver Enzymes: Lifestyle Changes and Treatment Options

If you have elevated liver enzymes, your healthcare provider may recommend various strategies to improve liver health:

Dietary modifications
Increased physical activity
Weight loss (if overweight or obese)
Alcohol reduction or cessation
Management of underlying conditions (e.g., diabetes, high cholesterol)
Medication adjustments

How effective are lifestyle changes in improving liver enzyme levels?

Lifestyle changes can be remarkably effective in improving liver enzyme levels. Many individuals see significant reductions in their liver enzyme levels within a few months of implementing healthier habits. For example, weight loss in overweight individuals can lead to substantial improvements in liver enzyme levels and overall liver health.

In some cases, more targeted treatments may be necessary, depending on the underlying cause of the elevated liver enzymes. These could include antiviral medications for hepatitis, immunosuppressants for autoimmune liver diseases, or other specific therapies as determined by your healthcare provider.

The Importance of Regular Liver Function Monitoring

Regular monitoring of liver function is crucial for maintaining overall health, especially for individuals with risk factors or a history of liver issues. Here’s why ongoing monitoring is important:

Early detection of liver problems
Tracking the effectiveness of treatments or lifestyle changes
Monitoring the progression of known liver conditions
Assessing the impact of medications on liver health

How often should liver function tests be performed?

The frequency of liver function tests depends on individual circumstances. For people with no known liver issues and no risk factors, annual testing as part of a routine health check-up may be sufficient. However, individuals with known liver conditions, those taking medications that can affect the liver, or those with persistent elevations in liver enzymes may need more frequent monitoring, possibly every 3-6 months or as recommended by their healthcare provider.

It’s important to work closely with your healthcare provider to determine the appropriate frequency of liver function tests based on your individual health profile and risk factors.

Emerging Research in Liver Health Assessment

The field of liver health assessment is continually evolving, with new research providing insights into more accurate and comprehensive evaluation methods. Some emerging areas of research include:

Non-invasive fibrosis assessment techniques
Advanced imaging technologies for liver evaluation
Genetic markers for liver disease susceptibility
Metabolomic profiling for early detection of liver dysfunction

How might future advancements change liver health assessment?

Future advancements in liver health assessment may lead to more personalized and precise evaluations. For instance, genetic testing could help identify individuals at higher risk for certain liver conditions, allowing for more targeted prevention strategies. Advanced imaging techniques may provide detailed information about liver structure and function without the need for invasive procedures. Metabolomic profiling could potentially detect subtle changes in liver metabolism long before traditional enzyme tests show abnormalities.

These advancements may allow for earlier detection of liver issues and more tailored treatment approaches, ultimately improving outcomes for patients with liver conditions.

The Role of Liver Health in Overall Wellness

The liver plays a crucial role in overall health and wellness, performing hundreds of essential functions in the body. Some key functions of the liver include:

Filtering toxins from the blood
Producing bile for digestion
Storing vitamins and minerals
Regulating blood sugar levels
Producing proteins essential for blood clotting
Metabolizing medications

How does liver health impact other body systems?

Liver health has far-reaching effects on various body systems. A healthy liver supports proper digestion, helps maintain stable energy levels, and contributes to a strong immune system. Conversely, liver dysfunction can lead to a range of health issues, including:

Fatigue and weakness
Digestive problems
Increased susceptibility to infections
Hormonal imbalances
Cognitive issues (in severe cases)

Maintaining optimal liver health is therefore crucial for overall wellness and longevity. Regular monitoring of liver function, along with healthy lifestyle choices, can help ensure that your liver continues to perform its vital functions efficiently.

Navigating Liver Health: Tips for Patients

If you’re concerned about your liver health or have been diagnosed with elevated liver enzymes, here are some practical tips to help you navigate your health journey:

Educate yourself: Learn about liver function and the factors that can affect liver health.
Communicate with your healthcare provider: Ask questions and ensure you understand your test results and treatment plan.
Be proactive about lifestyle changes: Implement healthy habits that support liver function.
Stay consistent with monitoring: Follow through with recommended follow-up tests and appointments.
Consider seeking a second opinion: If you’re unsure about your diagnosis or treatment plan, don’t hesitate to consult another specialist.
Join support groups: Connect with others who are managing liver health issues for support and shared experiences.

How can patients actively participate in their liver health management?

Patients can take an active role in managing their liver health by:

Keeping a journal of symptoms and potential triggers
Tracking their diet and exercise habits
Researching reputable sources to learn more about liver health
Preparing questions for their healthcare provider before appointments
Adhering to prescribed treatments and lifestyle recommendations
Regularly reviewing and updating their health goals with their provider

By taking an active role in their liver health management, patients can work more effectively with their healthcare providers to achieve optimal outcomes and maintain overall wellness.

What Level of Liver Enzyme Should I be Concerned With?

Are you having ongoing slight elevations in your liver enzymes?. Maybe you were told it is perfectly normal and you shouldn’t worry about it. In this article we go into some of the details of why that may or may not be appropriate for you. We look at what the optimal levels of liver enzymes are for males and females, so you can better understand what to do for your own health.

If you want to know what level of liver enzymes you should be concerned with keep reading.

What level of liver enzyme should I be concerned with? Mainly we are looking at this from the perspective of getting a blood test back that shows you have elevated liver enzymes. This could be the AST, the ALT or the GGT. AST is usually written out as as aspirate amino transferase. ALT is written out as alanine amino transferase. Most of the time the GGT isn’t done, but sometimes if you are looking specifically at a liver function test, the GGT will be included. There are a few other liver tests that may be included in a liver specific test. These are the three that are of most importance for assessing liver function.

In other articles we mentioned why these levels might be high. Also some other testing you might want to consider when you have elevated levels of these liver enzymes. These enzymes do come from your liver, but they can be found to a lesser extent in some other tissues as well. With all that being said, at what level should you start to be concerned when your liver enzymes are high? How high is too high?

The reference range for your liver enzymes will be slightly different from one lab to the next. Typically the level for the AST or aspirate amino transferase will be reported as between 10 and 40 units per liter. Alanine amino transferase will be between 7 to 56 units per liter. These are the reference ranges. If you fall within those parameters, you will not get flagged as high or low. Mild elevations are generally considered to be one or two times the normal limit. Moderate elevations are two to three times the reference range. Severely high levels are in the thousands. Then the question is, what do you do when your levels are in the sixties, seventies, or even fifties? Are these really a problem? Should you be concerned if your liver enzymes are on the upper end of normal or slightly above?

It is actually pretty common where to see the lab not flagging the results, but the level is slightly high. I see this very commonly in my practice. There is usually a good reason for it, but that doesn’t mean the level is actually in the optimal range. Optimal or a true healthy range for ALT is a range between 29 and 33 units per liter for males and slightly lower for females 19 to 25 units per liter. Levels consistently above this, meaning multiple tests that are higher than this, should be investigated. We’ are not getting into the causes here because there’s other articles on that topic.

Why Liver Enzymes Are High

The same approximate ranges can be used for the AST and GGT to make things simple and straightforward. I usually use 25 as a general reference range for both males and females. If it’s above that, that could be a problem. Of course, there’s some leeway depending on if you are a male or female and which tests we are actually looking at. That’s a rule of thumb that I usually go off of. Now, transient elevations, like one test above 25 is nothing to be concerned about. It is the consistent elevations, much more than 25, like 50, or even 30 that could be a problem. The level will really tell you what the next steps should be.

When it’s slightly above, it’s not really something to be concerned about. However, when the levels start to get into the upper end of the reference range like the fifties, that’s when you should start looking a little deeper. Especially if they are like that after multiple tests. So if you want more details on elevated liver enzymes, check out this videos. There’s also a very detailed paper that goes into a lot more detail on why we are establishing 25 as a normal, healthy, optimal liver enzyme range. The basis is, if you take a sick population and try and create a reference range from that, you get a sick reference range. The paper goes into a lot more detail.

That should give you a better understanding of what what level of liver enzymes should I be concerned with. If you have questions about the content in this article, please ask it in the comment section below.

If you want a customized plan on your elevated liver enzymes, click in the link below to get started.

Aspartate Aminotransferase (AST) Test | Kaiser Permanente

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Test Overview

An aspartate aminotransferase (AST) test measures the amount of this enzyme in the blood. AST is normally found in red blood cells, liver, heart, muscle tissue, pancreas, and kidneys. AST formerly was called serum glutamic oxaloacetic transaminase (SGOT).

Low levels of AST are normally found in the blood. When body tissue or an organ such as the heart or liver is diseased or damaged, additional AST is released into the bloodstream. The amount of AST in the blood is directly related to the extent of the tissue damage. After severe damage, AST levels rise in 6 to 10 hours and remain high for about 4 days.

The AST test may be done at the same time as a test for alanine aminotransferase, or ALT. The ratio of AST to ALT sometimes can help determine whether the liver or another organ has been damaged. Both ALT and AST levels can test for liver damage.

Why It Is Done

This test is done to:

Check for liver damage.
Help look for liver disease, such as hepatitis. Liver disease may cause symptoms. These may include pain in the upper belly, nausea, vomiting, and sometimes jaundice.
Check to see how well treatment for liver disease is working.
Find out if jaundice was caused by a blood disorder or liver disease.
Keep track of the effects of medicines that can damage the liver.

How To Prepare

In general, there’s nothing you have to do before this test, unless your doctor tells you to.

How It Is Done

A health professional uses a needle to take a blood sample, usually from the arm.

How long the test takes

The test will take a few minutes.

Watch

Learning About Your Blood Test
Learning About Blood Tests for Children

How It Feels

When a blood sample is taken, you may feel nothing at all from the needle. Or you might feel a quick sting or pinch.

Risks

There is very little chance of having a problem from this test. When a blood sample is taken, a small bruise may form at the site.

Results

Each lab has a different range for what’s normal. Your lab report should show the range that your lab uses for each test. The normal range is just a guide. Your doctor will also look at your results based on your age, health, and other factors. A value that isn’t in the normal range may still be normal for you.

Results are usually available within 12 hours.

High values

High levels of AST may be caused by:

Liver damage from conditions such as hepatitis or cirrhosis.
A heart attack or heart failure.
Many medicines, such as statins, antibiotics, chemotherapy, aspirin, opioids, and barbiturates.
Very strenuous exercise or severe injury to a muscle.
High doses of vitamin A.
Kidney or lung damage.
Mononucleosis.
Some types of cancer.

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Why It Is Done

Norm and interpretation of a biochemical blood test: basic indicators

Contents

1 Biochemical blood test: norm and a detailed description of indicators
- blood:
1. 2 What is a blood chemistry test?
1.3 How to properly prepare for a biochemical blood test?
- 1.3.1 Refusal of food
- 1.3.2 Stopping drugs
- 1.3.3 Stop smoking and exercise
- 1.3.4 Strict compliance with laboratory requirements
1.4 Key parameters of a biochemical blood test
- 1.4 .1 Total protein
- 1.4.2 Albumin
- 1.4.3 Glucose
- 1.4.4 Cholesterol
- 1.4.5 Creatinine
- 1.4.6 Amylase
1.5 blood and its meaning
1.6 Total blood protein: norm and interpretation
1.7 Blood cholesterol: norm and value
1.8 Triglycerides: norm and their significance for health
1.9 Creatinine: norm and interpretation
1.11 ALT and AST: norm and values parameters
- 1.11.1 Alanine aminotransferase (ALT)
- 1.11.2 Aspartate aminotransferase (AST)
3 related videos:
1.14 Q&A:
- - 1. 14.0.1 Why do a biochemical blood test?
  - 1.14.0.2 How to properly prepare for a biochemical blood test?
  - 1.14.0.3 What do the abbreviations ALT and AST mean in the analysis?
  - 1.14.0.4 What is the definition of blood sugar?
  - 1.14.0.5 Why is urea measured in a blood test?
  - 1.14.0.6 What is the normal level of cholesterol in the blood?

Find out what blood values should be normal and how to correctly interpret the results of a biochemical blood test. Useful information for those who care about their health and want to understand what the numbers on the tests mean.

A biochemical blood test is a study that allows you to find out the state of the internal organs and body systems. It is carried out by studying the ratio of various components of the blood, such as proteins, glucose, fats, minerals, etc. Thanks to a biochemical blood test, you can identify the presence of diseases and determine their severity.

The norms of a biochemical blood test depend on gender, age, physical activity and other factors. The results are interpreted by the doctor, who evaluates the presence of abnormalities and determines whether additional examination and treatment is required.

In this article we will consider the main components of a biochemical blood test, their norms and possible causes of deviations. You will learn how to properly prepare for analysis, what factors can affect the results, and how to correctly interpret the data.

Biochemical blood test: norm and value of parameters

Biochemical blood test is a laboratory diagnostic method that allows you to evaluate the work of organs and determine deviations in the biochemical composition of the blood. The results of the analysis include several parameters that have their own norms and values. The value of each parameter depends on the age and sex of the patient, his state of health and concomitant diseases.

Basic parameters of a biochemical blood test:

Glucose – norm in adults – 3. 33-5.55 mmol / l, in children – 3.33-5.55 mmol / l
Total protein – norm in adults – 64-84 g / l, in children – 42-78 g / l
Creatinine – the norm in adults – 44-106 μmol / l, in children – 18-35 μmol / l
Urea – the norm in adults – 2, 5-8.5 mmol / l, in children – 1.6-6.4 mmol / l
Cholesterol – the norm in adults – 3.6-7.8 mmol / l, in children – 2.6- 5.2 mmol/l

Deviations in the values of the parameters may indicate the presence of diseases of the organs and systems of the body, such as the liver, kidneys, heart, pancreas, and others. Upon receipt of the results of the analysis, it is imperative to consult a doctor who can correctly interpret the results and prescribe additional examination and treatment, if necessary.

What is a biochemical blood test?

Biochemical blood test is a laboratory diagnostic method that allows you to identify abnormalities in the functioning of organs and body systems. Biochemical analysis of blood is carried out by extracting from it the main components – proteins, fats, carbohydrates, minerals and other substances.

The data obtained help the doctor to determine the presence or absence of diseases, as well as the state of the body as a whole. The results of a biochemical blood test are used to monitor the treatment process and evaluate its effectiveness.

Typically, a blood chemistry test includes an assessment of the levels of glucose, proteins, lipids, enzymes, minerals, and many other substances.

Glucose is the main source of energy for the body. High glucose levels may indicate the development of diabetes.
proteins are the building blocks of tissues and cells. Low levels of proteins may indicate abnormalities in the functioning of the kidneys or liver.
Lipids are fats that are used for cellular metabolism. High lipid levels may indicate the development of atherosclerosis and other cardiovascular diseases.

A blood test requires a small amount of blood to be drawn from a vein in your elbow. The test results are usually ready the next day.

Blood components Normal values

Glucose	3.3 – 5.5 mmol/l
Proteins	60 – 8 0 g/l
Lipids	cholesterol less than 5.2 mmol/ l triglycerides less than 1.7 mmol/l

How to properly prepare for the analysis of a biochemical blood test?

Refusal of food

To correctly interpret the results of a blood test, it is necessary to donate blood on an empty stomach. This means that you must stop eating at least 8 hours before the procedure. However, drinking clean water is allowed. The body must be clean of food and alcohol in order to remove factors that can distort the results.

Cancellation of medications

When taking a blood test, all illnesses and medications taken must be reported to the medical staff. Medications can skew the results, so it is sometimes necessary to stop taking the medication for a few days before the analysis. However, the abolition of drugs is possible only after consultation with the doctor who prescribed the treatment.

Smoking cessation and exercise

Smoking before a blood test can also affect the results. It is better to stop smoking at least one hour before the test. Physical exercise is also not advisable before the examination, as it increases the level of certain elements in the blood, which may affect the results of the study.

Lab Strict Compliance

Each lab may have its own requirements for patient preparation prior to analysis. Therefore, it is necessary to check the list of recommendations in advance or receive instructions from a doctor. All requirements must be strictly observed in order to obtain correct analysis results.

Basic parameters of a biochemical blood test

Total protein

Total protein is the total amount of protein in blood plasma, including globulins and albumin. Usually taken value for this parameter is in the range of 65-85 g/l for adults. Deviation from this norm can indicate various diseases, including dysfunction of the liver, kidneys, tumors, etc.

Albumin

Albumin is one of the most abundant proteins in the blood. It performs a number of basic functions, such as maintaining oncotic pressure, transporting hormones, drugs, etc. The normal level of albumin in the blood is 35-50 g/l in adults. A decrease in albumin levels may indicate diseases of the liver, kidneys, hypoalbuminemia, etc.

Glucose

Glucose is the main source of energy for cells. Normally, your blood glucose level should be in the range of 3.3-5.5 mmol/L, but this value can vary depending on diet, physical activity, and the presence of diseases such as diabetes.

Cholesterol

Cholesterol is a fat-like substance necessary for the formation of cell membranes and the production of hormones. However, excess cholesterol can lead to various diseases such as atherosclerosis. The normal level of cholesterol in the blood is less than 5.2 mmol/l.

Creatinine

Creatinine is a product of creatine metabolism used by the body for muscle energy. Elevated creatinine levels can indicate impaired kidney function, as well as other diseases. The creatinine level is usually 44-106 µmol/l for men and 36-92 µmol/l for women.

Amylase

Amylase is an enzyme that catalyzes the breakdown of carbohydrates in the intestine. Elevated amylase levels can indicate pancreatic disease and other diseases. The normal amylase level is 25-125 U/L.

Parameters Norm

Total protein	65-85 g/l
Albumin	35-50 g/l 901 60
Glucose	3.3-5.5 mmol/l
Cholesterol	less than 5.2 mmol/l
Creatinine	44-106 µmol/l for men 36-92 µmol/l for women 90 160
Amylase	25-125 E/ l

Blood glucose norm and its value

Glucose is one of the most important molecules that supply energy to the body. In the blood, glucose has the value of an indicator that is controlled by a biochemical blood test.

In addition, blood glucose levels may vary depending on the time of day and food intake. Typically, fasting blood glucose levels are lower than two hours after a meal.

Blood glucose levels below normal may indicate hypoglycemia. Symptoms of hypoglycemia may include weakness, dizziness, and loss of consciousness.
High blood glucose levels may indicate hyperglycemia. Symptoms of hyperglycemia may include polyphagia, polydipsia and polyuria, frequent headaches, and drowsiness.

Thus, the norm of glucose in the blood is an important indicator of the state of the body and requires regular monitoring. If the level of glucose in the blood is not normal, then you need to consult a doctor and undergo appropriate studies to identify the cause of the pathology.

Total blood protein: norm and interpretation

Total blood protein is the sum of all types of proteins in blood plasma. The normal level for an adult is 66 to 83 g/L.

A low total protein level can indicate various conditions such as: liver and kidney disease, insufficient dietary protein intake, overhydration, etc. An increased protein level can be associated with infectious diseases, oncological diseases, bone marrow diseases, etc.

Additional testing is needed to determine the cause of the change in total protein. For example, an analysis of the albumin protein content in the blood can help determine a protein imbalance and point to the specific cause of a change in total protein levels.

Norm: 66-83 g/l
Decreased level: may indicate diseases of the liver and kidneys, insufficient intake of protein from food
Increased level: may be associated with infection diseases, oncological diseases, bone marrow diseases

Protein Normal Increased level Decreased level

9015 9 diseases of the liver and kidneys, insufficient intake of protein from food

Total blood protein

66-83 g/l

infectious diseases, oncological diseases, bone marrow diseases

Cholesterol in the blood: norm and value

Cholesterol is an important lipid that is necessary for the normal functioning of the body. However, with an excess of cholesterol in the blood, serious diseases can develop.

There are two types of cholesterol: “good” HDL-C and “bad” LDL-C. The normal HDL-C level should be above 1 mmol/l in men and 1.2 mmol/l in women, and the LDL-C level should not exceed 3 mmol/l.

An increase in the level of cholesterol in the blood can be caused by malnutrition, obesity, heredity, malignant tumors and other factors.

It is important to monitor your blood cholesterol levels and, if necessary, take measures to lower them, such as proper nutrition, regular exercise, and medication prescribed by your doctor.

Triglycerides: the norm and their importance for health

Triglycerides are fatty acids that are stored in fat cells and used as an energy source. They can also be obtained from foods, especially those rich in fat.

Normal blood levels of triglycerides vary with age and sex. The total level should not exceed 150 mg/dl. If triglyceride levels are higher than normal, this may indicate a risk of developing cardiovascular disease, diabetes, and other diseases.

To reduce triglyceride levels, the following is recommended:

Reduce fatty foods and fast carbohydrates;
Increase intake of plant foods, fish, nuts;
Maintain a healthy weight and be physically active.

Triglycerides are an important indicator of health and should be monitored, especially in people at increased risk of disease.

Creatinine: norm and interpretation

Creatinine is a metabolic product produced in the muscles and excreted through the kidneys. Creatinine is used to evaluate kidney function. Normal values of creatinine in the blood vary depending on the sex and age of the person.

Elevated creatinine may indicate kidney problems. This may be associated with diseases such as chronic renal failure, glomerulonephritis, pyelonephritis, and others.

Normal blood creatinine Men (mg/dl) Women (mg/dl) 0163

Increased level over 1.

3 more than 1.1 Reduced level less than 0.7 less than 0.5

Blood urea: normal and its meaning

Urea is one of the products of nitrogen metabolism in human body. It is formed in the liver and excreted through the kidneys. The content of urea in the blood may vary depending on the state of the organism. Elevated levels of urea in the blood can be associated with diseases of the kidneys, liver and other organs. It is important to know the rate of urea in the blood and its significance for assessing health.

The normal blood urea level in adults is usually between 2.5 and 6.4 mmol/L. Urea levels can increase with exercise, protein intake, certain medications, and during pregnancy in women. However, if the level of urea exceeds the norm, this may be a sign of pathological changes in the body.

Elevated blood urea levels may be associated with kidney and liver disease, as well as cardiovascular and blood disorders. If the level of urea exceeds the norm, it is necessary to consult a doctor to find out the cause of this condition and prescribe the appropriate treatment.

Conclusion: the norm of urea in the blood is from 2.5 to 6.4 mmol / l.
Meaning: The blood urea level can be a key indicator in the diagnosis of many diseases, especially those related to the functioning of the kidneys and liver. With an increase in the level of urea, it is necessary to consult a doctor to find out the cause and prescribe treatment.

ALT and AST: normal and parameter values

Alanine aminotransferase (ALT)

ALT is an enzyme that is actively involved in the conversion of amino acids in liver cells. If the liver is damaged or diseased, the level of ALT in the blood can increase significantly.

The normal level of ALT in men is up to 45 units/l, in women it is up to 34 units/l.
Elevated ALT levels may indicate liver disease such as hepatitis, cirrhosis, or liver cancer.
ALT elevations can also be caused by certain drugs or alcohol.

Aspartate aminotransferase (AST)

AST is another enzyme involved in amino acid metabolism. This enzyme is found not only in the liver, but also in the heart, muscles and other organs. When these organs are damaged, the level of AST in the blood rises.

The normal level of AST in men is up to 41 units/l, in women it is up to 31 units/l.
An increase in AST may indicate damage to the heart, muscles, or other organs.
AST levels may also increase with certain medications or during intense physical activity.

It is important to remember that when determining the level of ALT and AST in the blood, it is necessary to take into account indicators of other biochemical parameters and conduct additional studies to determine the exact cause of the increase in enzyme levels.

Deciphering a biochemical blood test: basic indicators

Total protein is the main indicator of the state of protein metabolism in the body. Its level allows you to determine the presence or absence of diseases of the liver, kidneys or blood.

Glucose is the main source of energy for all cells of the human body. Diabetes can occur when blood glucose levels are elevated, and if glucose levels are too low, hypoglycemia can occur.

Creatinine is a metabolic product of creatine, which is formed in the muscles and excreted through the kidneys. The level of creatinine in the blood allows you to evaluate the work of the kidneys and determine the presence or absence of their diseases.

Urea is the end product of protein metabolism. An elevated level of urea indicates a violation of the functions of the kidneys and liver.

Bilirubin is a yellow pigment produced by the breakdown of hemoglobin. Elevated levels of bilirubin in the blood may indicate a disease of the liver or biliary tract.

Cholesterol is an important element of cell membranes and a hormone precursor. However, with its elevated level, various cardiovascular diseases are possible.

To summarize:

Biochemical blood test is an integral part of the medical examination. As a result of this analysis, it is possible to determine the state of various body systems. The main indicators of the analysis are total protein, glucose, creatinine, urea, bilirubin and cholesterol. Maintaining the level of these indicators in the norm is important for human health.

Q&A:

Why do a biochemical blood test?

A biochemical blood test is needed to determine the level of various substances in the body, such as proteins, hormones, minerals, fats, and others. This allows you to evaluate the work of various organs and systems, as well as identify possible diseases.

How to properly prepare for a biochemical blood test?

Before taking the test, you must abstain from food for 8-12 hours, drink only water. It is also necessary to avoid physical activity, stress, alcohol and smoking 24 hours before the analysis.

What do the abbreviations ALT and AST mean in the analysis?

ALT (alt) and AST (ast) are indicators that characterize the functioning of the liver. ALT is responsible for the process of amino acid metabolism, and AST is responsible for the energy exchange process. An increase in these indicators may indicate violations in the liver.

What is the definition of blood sugar?

Blood sugar is assessed by two indicators – fasting glucose and glycated hemoglobin. An increase in these indicators may indicate diabetes mellitus or other disorders of carbohydrate metabolism in the body.

Why is urea measured in a blood test?

Urea is a protein metabolic end product that is formed in the liver and excreted through the kidneys. An increase in the level of urea may indicate a malfunction of the kidneys, liver or other organs.

What is the normal level of cholesterol in the blood?

The normal level of cholesterol in the blood depends on age and sex. Total cholesterol should be less than 5 mmol/L. An increase in cholesterol levels increases the risk of cardiovascular disease.

Analysis norms. Analysis decoding. Reference values, interval. “Norm” and “pathology” in laboratory diagnostics.

This article describes what test norms are, how tests are deciphered, why it is not modern to say “norm”, and what are reference values and reference intervals.

Standards for interpretation of tests. Concept of reference values and reference interval.

The information obtained in the course of laboratory analysis is based on the detection and / or measurement in clinical samples (biomaterial) of patients of certain components – analytes, functionally or structurally related to a specific human organ or organ system. The most important component of any laboratory research is the interpretation of its result. Establishing the difference between the norm of analyzes and pathology plays a key role in assessing the data obtained. In practice, this is not difficult to do with a clear deviation of laboratory parameters from the values taken as the norm. However, it is not always easy to divide most of the results of laboratory tests into “normal” and “pathology”, and therefore, in order to interpret them, a comparison of the data obtained with the indicators established as the norm is required.

Normal test values (normal) are values found in healthy people. However, in the groups of the latter, they can have different values, that is, the norm is individual. This is due both to the individual physiological characteristics of the human body (characteristics of metabolism, circadian biological rhythms, the functional state of certain organs and their systems), and differences in gender, age, and physiological state. For example, during pregnancy, many biochemical parameters of a woman’s body change, therefore, appropriate individual norms are determined for pregnant women.

Normal laboratory values are determined in experimental clinical studies based on the results of measurements of the analyte under investigation in a large population of healthy people, specially selected and grouped by age, sex or other biological and other factors. The data obtained lead to the mean value, taking into account the statistically possible standard deviations of its value. In this regard, it is more correct to speak not about the “norm” of a laboratory indicator, but about the range in which normal (reference) values are located. Therefore, at present, the term “norm”, which has already become familiar in assessing the results of a laboratory study, is used less frequently. Instead, they talk about reference (reference) values  and the results obtained for a particular patient are compared with the so-called reference interval (range) . This term is more accurate, because it gives an idea of the lower and upper limits of the norm of a laboratory indicator, possible, statistically significant limits of fluctuation (deviation) of its value and, at the same time, emphasizes the relativity of these data, the possibility of applying only to a certain group of people.

Explanation of analyzes. Norm or pathology?

When establishing the reference range, mathematical and statistical approaches are used, according to which the values of the results of laboratory studies of a certain analyte of 95% of healthy people fall within the established interval. Accordingly, for 5% – the values of the analyzed indicators are outside the established range. In other words, in 5% of cases in healthy people, “abnormal” laboratory parameters are detected, which should be taken into account when deciphering the analysis. This is explained by a number of reasons.

First, the division of the biological population of people into “sick” and “healthy” according to many laboratory parameters is very conditional. Being statistical data, the limits of normal laboratory values may vary. Therefore, it happens that in healthy people certain indicators that are “normal” for them are not ultimately “normal” for most others, and therefore do not fall into the range of generally accepted reference values. In this case, the limits of the reference range cannot serve as absolute indicators of health or disease.

On the other hand, often the disease develops imperceptibly, manifesting itself as a gradual transition from small deviations in the values of laboratory parameters to their higher values as dysfunction increases and the severity of the disease progresses. In this regard, when deciphering the analyzes in interpreting the results of laboratory tests, it becomes very important for the clinician to assess the dynamics of changes in a particular laboratory indicator in a particular patient. In doubtful cases, the main criterion for the presence or absence of a disease is the clinical symptomatology or the degree of its severity. In the presence of symptoms of the disease, additional laboratory tests are used for diagnosis using highly sensitive and specific tests that most pronouncedly change their values against the background of the suspected disease.

Secondly, “healthy” and “sick” people actually belong to two different populations, and when these populations are mixed together, it is almost impossible to recognize each of them in the total mass. In addition, in different patients, the same indicator can not only take on different values, but also overlap the values of this indicator in healthy people. Moreover, for different indicators, different diseases, different groups of patients, the value of such a “cross” can vary greatly: from too small, which can be neglected, to very significant, when a special approach and careful analysis of all data is required to classify the result as “normal” or “pathological”. The latter is extremely important to take into account when evaluating the results of laboratory tests, since in this case not all values that are outside the normal range will indicate the presence of pathology. The range of values in which the laboratory parameters of “sick” and “healthy” individuals overlap is called the zone of uncertainty, or the “gray zone”. It exists for a range of laboratory procedures, but is most commonly found in enzyme immunoassay results. If the result falls into the “gray zone”, it cannot be unequivocally regarded either as a norm or as a pathology and is considered as doubtful. In such a case, the patient is usually advised to repeat the diagnostic study 2 to 4 weeks after receiving an indeterminate result.

And, finally, not always an indicator lying in the reference interval can be considered normal, since the range of many of them is quite wide. For example, the normal value of hematocrit (Ht) in men varies from 42 to 52%. Massive blood loss can lead to a drop in this indicator from 52 to 42%, while the value of 42% remains within the range of reference values, and therefore may not cause alarm for doctors. However, in a certain situation, for a particular patient, such a decrease in hematocrit can be not only clinically significant, but also critical.

Therefore, results within the reference range are not always normal. And, on the contrary, the results that go beyond the reference values are not always pathology, but only a significant prognostic sign that can signal a possible pathological process. In this regard, in laboratory diagnostics, the approach is becoming more widespread, when the most significant and adequate reference values for each individual patient should be considered stable results of his laboratory studies obtained over several years. Already at present, experts around the world are inclined to believe that it is necessary to “lower” the significance of reference intervals, moving away from interpreting them as some kind of “absolute” criterion for evaluating a laboratory result. This circumstance in no way reduces the importance of laboratory research. They remain the most important tool for diagnosing pathological conditions, monitoring the course of diseases, identifying the preclinical stage of diseases during screening examinations, and also largely determine the further tactics of diagnostic procedures and treatment decisions. However, this approach directs the clinician to a more cautious use of reference values in the assessment of “normal” and “pathological” results, indicating the need for their interpretation, taking into account possible biological variation in the population, taking into account the data of the clinical picture and other types of studies in the aggregate, and as well as those factors that may influence the results of laboratory tests.

Reference ranges

Reference values have now been established for many laboratory parameters. The results of some types of research are given to the patient in the form of “yes” or “no”. This type of research is qualitative. For example, a positive result for antibodies to a specific infection indicates the presence of these antibodies in the patient’s blood and may indicate infection. In the case when the study was quantitative, the result is issued as a numerical value, indicating on the form the units of measurement and the corresponding reference range. For example, the results of a biochemical study to determine the level of C-reactive protein (CRP), which is a marker of inflammation, may look like this: 0.4 mg / l, reference values: 0 – 6 mg / l. From the above example, it can be seen that the result obtained is within the established reference range. For most laboratory parameters, the range of reference values is indicated taking into account the patient’s gender and / or his belonging to a certain age group. For example, the reference values of serum creatinine for children under 1 year old are 18 – 35 µmol / l, for children from one to 14 years old – 27 – 62 µmol / l, and for people over 14 years old – 62 – 115 µmol / l for male and 53 – 97 µmol/l for females.

The influence of age and sex on the range of reference values is significant for many laboratory tests. For example, the concentration of alkaline phosphatase, a key enzyme secreted by bone tissue cells, increases in proportion to the rate of formation of new bone cells. Therefore, in children and adolescents, a high level of this enzyme is not only normal, but also desirable, since it is associated with the active formation and growth of bones. On the contrary, a high level of alkaline phosphatase in an adult may indicate developing osteoporosis, metastases of bone tumors, or other pathological processes. The exception is pregnant women, who are characterized by a physiological increase in the activity of this enzyme, especially in the third trimester of pregnancy.

Why can reference ranges vary from laboratory to laboratory?

Different diagnostic laboratories use different types of laboratory equipment to perform analysis, for example, biochemical and immunochemical analyzers, the range of which is currently very wide, work on reagents from different manufacturers, and in addition, they may use different research methods than other laboratories . In this regard, each laboratory indicates on the form of results its ranges of reference values, when establishing which, of course, it is guided by generally accepted standards, but taking into account the individual characteristics of its work: the specifics of the equipment used, the methods of analysis used and units of measurement. That is why the ranges of reference values for the same laboratory test may vary according to the data of different diagnostic laboratories, and there is no such thing as a “single” reference range. When evaluating the results of laboratory tests, the attending physician should first of all refer to the range of reference values indicated on the form of the laboratory in which the analysis was performed. In order for the results to be interpreted correctly and comparable, especially in the case of repeated studies, for example, when monitoring therapy or dynamic assessment of the patient’s condition, it is advisable to conduct studies using the same method, in the same laboratory and, if possible, ceteris paribus.

Factors affecting laboratory results

Modern methods of clinical laboratory research are characterized by high sensitivity and specificity, and therefore their results, reflecting the patient’s health, can serve as the basis for making important clinical decisions by the attending physician. At the same time, both clinicians and patients should understand that there are a number of non-pathological factors that can, to a certain extent, influence the results of laboratory tests, distorting the objective picture of the patient’s health. Some of these factors can only be controlled by the efforts of laboratory specialists, minimizing their possible negative impact on the final result of the laboratory study. Among such factors, for example, the conditions and method of taking biological material, delivery and storage of samples, the correctness of their identification in the laboratory. However, to minimize the negative impact of many other factors that affect the accuracy of the final result of a laboratory test, only the patient himself or his attending physician, who must inform the patient about the correct preparation for a certain type of laboratory test, can. Compliance with the doctor’s instructions will allow the analysis to be as close as possible to the general requirements, for example, the need to donate blood on an empty stomach, and thereby bring the results of the study as close as possible to the reference ones for this group of patients.

What factors can influence the results of laboratory tests? First of all, it should be noted the sensitivity of many laboratory tests to the time interval associated with the patient’s intake of food in general or individual products in particular, as well as the peculiarities of his eating behavior, for example, diet (meat or vegetarian), coffee and alcohol consumption. For example, high blood sugar may be related to a recent meal rather than diabetes. Eating shortly before the study will affect the results of lipid profile tests, insulin and C-peptide levels. In this regard, in order to obtain accurate results of the study, it is recommended to donate blood in the morning on an empty stomach, usually not less than 8 and not more than 14 hours after the last meal. On the eve of the study, food overload should be avoided.

High levels of liver enzymes may be due to recent or frequent alcohol use. Caffeine can cause an increase in the concentration of catecholamines and renin in plasma. Smoking sometimes causes a borderline increase in the level of some tumor markers.

Lab test results may be affected by vitamin and nutritional supplements and medications. In this case, the effect of drugs can be multidirectional. They can not only change the physiological processes in the body, but also chemically interfere (interact) with the analyzed analyte under conditions in vitro . An example of the effect of drugs on the physiological level is the increase in liver enzymes under the influence of hepatotoxic drugs. Drugs that affect plasma volume can cause changes in the concentration of proteins, urea nitrogen, iron and calcium. An example of another influence is non-specific binding reactions of certain drug metabolites with individual components of the reaction mixture, for example, polyclonal antibodies in immunoassays, as a result of which an erroneous result can be obtained. In this regard, a patient taking any medications should consult with a doctor about the advisability of conducting a laboratory study while taking medications or the possibility of stopping them before the study.

Among the factors affecting the results of laboratory tests is physical activity. Physical stress leads to a volumetric shift between the vascular bed and the intercellular space, loss of fluid with sweat and, as a result, to a change in the concentration of some analytes: hormones or enzymes. Therefore, visiting, for example, a gym on the eve of a laboratory test is undesirable. Heavy physical activity can cause an increase in the level of certain enzymes (ALT, AST, LDH, creatine kinase), a change in the level of various blood substrates (glucose, urea, etc.), and increase the excretion of protein in the urine. In addition, people who have been actively involved in sports for a long time, such as long-distance running or weightlifting, may have slightly increased levels of testosterone and luteinizing hormone (LH).

A general recommendation to prepare for the test is to rest (preferably sit) for 10 to 20 minutes after arriving at the laboratory before taking blood samples. This is also due to the fact that the results of some laboratory tests can be influenced by the body position of the subject at the time of its conduct, as well as the emotional state of the person before and during the study. So, for example, a change in body position from a lying position to a sitting or standing position causes vasoconstriction, and a change in position from a sitting to a lying position causes a shift of water and electrolytes in the tissue, leading to blood concentration. As a result, serum or plasma levels of total protein, albumin, lipids, iron and calcium change upward.

Emotional stress can cause significant increases in cortisol, ACTH and glucose levels. Among other things, stress is combined with an increase in the concentrations of albumin, fibrinogen, insulin, lactate and cholesterol. That is why it is so important, if possible, to exclude psycho-emotional stress on the eve of the study and try not to worry in the process of taking a biological sample.

Temporary changes in some laboratory parameters may be caused by physiotherapy and instrumental examinations (eg, prostate biopsy before PSA testing). In such cases, it is recommended to postpone the laboratory examination for several days.

For a number of hormonal studies, it is important to take into account the phase of the menstrual cycle in women, and therefore you should check with your doctor in advance the optimal days for blood donation to determine the level of FSH, LH, inhibin B, prolactin, progesterone, estradiol and some other hormones.

Time of day during sampling is especially important when cortisol, thyroid stimulating hormone (TSH), and certain other analytes are needed. At the same time, it should be borne in mind that the reference values - the boundaries of the “normal” laboratory parameters, usually reflect the statistical data obtained under standard conditions when taking blood in the morning.

Thus, there are a number of reasons why the results of the analysis may fall outside the established range of reference values, even if the person is absolutely healthy. Therefore, if the patient is aware of any special circumstances that could affect the results of the studies, they should be reported to their doctor. Don’t expect him to figure them out on his own. After all, a result that does not correspond to the “norm” is not necessarily a sign of a disease, and therefore the doctor needs to understand its possible cause. It is possible that this is just the case when the result obtained falls into those very statistically significant 5%, in which the laboratory parameters of healthy people are outside the reference range. Sometimes some “abnormal” results can go back to normal on their own, especially if they were on the border of the reference values. In addition, there are not many diseases that can be diagnosed with just one single test.

The above examples show that in order to adequately evaluate the results of laboratory tests, as well as to make the right clinical decisions for the patient on the basis of them, a comprehensive approach is needed that takes into account all the variety of factors that can affect the accuracy and correctness of the data obtained. . Clinical conclusions and decisions based on the results of laboratory analyzes will be correct only if the various preanalytical and analytical factors are sufficiently standardized and fully taken into account. It is very important that the patient be able to follow all the necessary recommendations for preparing for laboratory tests, and the attending physician, interpreting the data obtained, would take into account the possible impact on the result of the study of non-pathological factors that occurred, and also comprehensively evaluate the results, taking into account the clinical picture and data from other types research.

Laboratory diagnostics specialists, if necessary, are always ready to answer questions on the results obtained, provide additional special information and explanations or consult in complex cases.