What are liver function tests. How do they help monitor liver health. What causes elevated liver enzymes. When should you get tested. How to interpret liver test results.

The Importance of Liver Function Tests in Assessing Health

Liver function tests play a crucial role in evaluating the overall health of one of our body’s most vital organs. These blood tests measure various proteins, enzymes, and substances that provide valuable insights into the liver’s performance. By analyzing these markers, healthcare professionals can detect potential liver issues, monitor existing conditions, and assess the effectiveness of treatments.

Understanding liver function tests is essential for anyone concerned about their liver health or undergoing medical evaluations. Let’s delve into the specifics of these tests, their purposes, and what elevated results might indicate.

Common Types of Liver Function Tests

Several tests are typically included in a comprehensive liver function panel. Each test measures a specific component in the blood that reflects different aspects of liver health:

• Alanine transaminase (ALT) test
• Aspartate aminotransferase (AST) test
• Alkaline phosphatase (ALP) test
• Albumin test
• Bilirubin test

Alanine Transaminase (ALT) Test

ALT is an enzyme primarily found in liver cells. When liver cells are damaged, ALT is released into the bloodstream. An elevated ALT level often indicates liver damage or disease.

Did you know approximately 10% of Americans have elevated ALT levels? This statistic underscores the prevalence of potential liver issues in the population and highlights the importance of regular liver function monitoring.

Aspartate Aminotransferase (AST) Test

AST is an enzyme found in various body tissues, including the liver, heart, and muscles. While not as specific to liver function as ALT, elevated AST levels can still indicate liver problems when considered alongside other test results.

Interestingly, the ratio of AST to ALT can provide additional diagnostic information. For instance, a high AST:ALT ratio may suggest alcoholic liver disease, offering valuable clues for healthcare providers in determining the underlying cause of liver dysfunction.

Alkaline Phosphatase (ALP) Test

ALP is an enzyme present in several organs, including the liver, bones, and bile ducts. In liver function testing, ALP levels are particularly useful for evaluating the bile duct system. Elevated ALP levels may indicate obstructions in bile flow or certain liver diseases.

Albumin Test

Albumin is the main protein produced by the liver. It serves numerous essential functions, such as nourishing tissues and transporting hormones and vitamins throughout the body. Low albumin levels may suggest impaired liver function or malnutrition.

Bilirubin Test

Bilirubin is a yellowish pigment produced during the breakdown of red blood cells. The liver processes bilirubin before it’s excreted from the body. Elevated bilirubin levels can indicate liver dysfunction or certain inherited conditions affecting bilirubin metabolism.

When Are Liver Function Tests Recommended?

Healthcare providers may recommend liver function tests in various scenarios:

1. Screening for liver diseases like hepatitis B and C
2. Monitoring potential side effects of medications
3. Assessing the progression of known liver conditions
4. Evaluating symptoms suggestive of liver disorders
5. Routine health check-ups, especially for individuals with risk factors

Are you at risk for liver disease? Consider discussing liver function tests with your healthcare provider if you have a family history of liver disorders, consume alcohol frequently, or have conditions such as diabetes, high blood pressure, or high triglycerides.

Interpreting Liver Function Test Results

Interpreting liver function test results requires medical expertise, as many factors can influence the outcomes. Generally, results outside the typical range may indicate potential liver issues, but it’s crucial to consider the entire clinical picture.

Here’s a brief overview of what atypical results might suggest:

• Elevated ALT and AST: Possible liver cell damage
• High ALP: Potential bile duct obstruction or certain liver diseases
• Low albumin: Impaired liver function or malnutrition
• Elevated bilirubin: Liver dysfunction or inherited metabolic disorders

Keep in mind that even mildly elevated results can be associated with liver disease. Always consult with your healthcare provider to understand the implications of your specific test results.

Causes of Elevated Liver Enzymes

Elevated liver enzymes can result from various factors, ranging from temporary conditions to chronic liver diseases. Some common causes include:

• Viral hepatitis (hepatitis B, C)
• Alcoholic liver disease
• Nonalcoholic fatty liver disease (NAFLD)
• Certain medications (e.g., statins, antibiotics, NSAIDs)
• Autoimmune liver diseases
• Metabolic disorders
• Liver tumors or cancer

Understanding the underlying cause of elevated liver enzymes is crucial for appropriate treatment and management. Your healthcare provider may recommend additional tests or imaging studies to determine the specific cause of your elevated liver enzymes.

Preparing for Liver Function Tests

Proper preparation is essential for accurate liver function test results. While specific instructions may vary depending on the test and your healthcare provider’s recommendations, here are some general guidelines:

• Fasting: Some tests may require fasting for 8-12 hours before the blood draw.
• Medication review: Inform your healthcare provider about all medications and supplements you’re taking, as some may affect test results.
• Alcohol abstinence: Avoid alcohol consumption for at least 24 hours before the test.
• Hydration: Unless instructed otherwise, stay well-hydrated before the test.

Always follow your healthcare provider’s specific instructions to ensure the most accurate test results.

Recognizing Signs of Liver Dysfunction

While liver function tests are invaluable for detecting liver issues, it’s also important to be aware of potential symptoms that may indicate liver problems. Common signs of liver dysfunction include:

• Fatigue and weakness
• Unexplained weight loss
• Jaundice (yellowing of skin and eyes)
• Abdominal pain or swelling
• Nausea or loss of appetite
• Dark urine or pale stools
• Easy bruising or bleeding

If you experience any of these symptoms, especially in combination, it’s crucial to consult your healthcare provider promptly. Early detection and intervention can significantly improve outcomes for many liver conditions.

The Impact of Lifestyle on Liver Health

Your lifestyle choices can have a profound impact on liver health. Consider the following factors that influence liver function:

• Alcohol consumption: Excessive alcohol intake is a leading cause of liver disease.
• Diet: A balanced diet rich in fruits, vegetables, and whole grains supports liver health.
• Exercise: Regular physical activity helps maintain a healthy weight and reduces the risk of fatty liver disease.
• Hydration: Adequate water intake supports optimal liver function.
• Stress management: Chronic stress can negatively impact liver health.

By adopting a liver-friendly lifestyle, you can support your liver’s function and potentially reduce the risk of developing liver problems.

Advances in Liver Function Testing and Diagnosis

The field of liver function testing continues to evolve, with new technologies and approaches enhancing our ability to detect and monitor liver diseases. Some recent advancements include:

• Non-invasive imaging techniques: FibroScan and magnetic resonance elastography (MRE) can assess liver fibrosis without the need for a biopsy.
• Genetic testing: Identifying genetic markers associated with certain liver diseases can aid in early diagnosis and personalized treatment.
• Biomarker panels: Comprehensive panels of biomarkers can provide more detailed information about liver health and disease progression.
• Artificial intelligence: Machine learning algorithms are being developed to improve the interpretation of liver function test results and predict disease outcomes.

These advancements offer promising opportunities for more accurate and timely diagnosis of liver conditions, potentially leading to improved patient outcomes.

The Role of Liver Function Tests in Monitoring Chronic Liver Diseases

For individuals with chronic liver diseases, regular liver function tests play a crucial role in monitoring disease progression and treatment efficacy. Conditions that often require ongoing liver function monitoring include:

• Chronic viral hepatitis (B and C)
• Autoimmune hepatitis
• Primary biliary cholangitis
• Nonalcoholic fatty liver disease (NAFLD)
• Alcoholic liver disease
• Cirrhosis

By tracking changes in liver function test results over time, healthcare providers can assess the effectiveness of treatments, adjust medications as needed, and identify potential complications early.

Liver Health and Overall Wellness

The liver’s role in overall health cannot be overstated. As a central organ in metabolism, detoxification, and immune function, the liver’s well-being is intricately linked to our general health and quality of life. Understanding the importance of liver function tests and maintaining good liver health can contribute significantly to overall wellness.

Consider these facts about liver health and its impact on overall wellness:

• The liver performs over 500 vital functions in the body.
• Liver disease affects approximately 4.5 million adults in the United States.
• Many liver diseases are preventable through lifestyle modifications.
• Early detection and treatment of liver problems can prevent or slow the progression to more serious conditions.

By prioritizing liver health through regular check-ups, healthy lifestyle choices, and awareness of potential risk factors, you can support not only your liver but your overall health and well-being.

Liver Function Tests in Special Populations

While liver function tests are valuable tools for assessing liver health in the general population, certain groups may require special considerations or modified approaches to testing:

• Pregnant women: Pregnancy can affect liver function test results, and some liver conditions specific to pregnancy require careful monitoring.
• Children: Reference ranges for liver function tests may differ in pediatric populations, and interpretation should consider age-specific norms.
• Elderly individuals: Age-related changes in liver function and increased prevalence of certain conditions may influence test results and interpretation.
• Individuals with genetic liver disorders: Certain inherited conditions may require specialized testing or more frequent monitoring.

Healthcare providers consider these factors when ordering and interpreting liver function tests, ensuring that results are appropriately contextualized for each individual.

Emerging Trends in Liver Health Management

As our understanding of liver function and disease continues to grow, new approaches to liver health management are emerging. Some promising trends include:

• Precision medicine: Tailoring treatments based on an individual’s genetic profile and specific disease characteristics.
• Liver-targeted drug delivery: Developing medications that specifically target liver cells to improve efficacy and reduce side effects.
• Regenerative medicine: Exploring stem cell therapies and bioengineered liver tissues to treat severe liver diseases.
• Digital health technologies: Utilizing wearable devices and smartphone apps to monitor liver health and support lifestyle modifications.
• Gut microbiome research: Investigating the relationship between gut bacteria and liver health to develop new therapeutic approaches.

These emerging trends hold promise for improving the diagnosis, treatment, and management of liver diseases in the future.

The Global Burden of Liver Disease

Liver disease is a significant global health concern, with varying prevalence and causes across different regions. Consider these global perspectives on liver health:

• Viral hepatitis remains a major cause of liver disease worldwide, with hepatitis B being particularly prevalent in parts of Asia and Africa.
• Alcoholic liver disease is a significant concern in many developed countries.
• Nonalcoholic fatty liver disease is increasing globally, paralleling the rise in obesity and metabolic syndrome.
• Access to liver function testing and treatment varies widely between high-income and low-income countries.

Understanding the global context of liver disease highlights the importance of public health initiatives, research, and international cooperation in addressing this widespread health issue.

Empowering Yourself with Liver Health Knowledge

Knowledge is power when it comes to maintaining liver health. By understanding the importance of liver function tests, recognizing risk factors, and adopting liver-friendly lifestyle habits, you can take proactive steps to support your liver and overall health.

Consider these actionable steps to empower yourself:

• Schedule regular check-ups with your healthcare provider, including liver function tests when appropriate.
• Learn about your family history of liver disease and discuss any concerns with your doctor.
• Educate yourself about the effects of alcohol, medications, and dietary choices on liver health.
• Stay informed about new developments in liver health research and treatment options.
• Advocate for liver health awareness in your community.

By taking an active role in your liver health, you can contribute to a healthier future for yourself and inspire others to do the same.

Liver Function Tests: Purpose, Procedure, and Results

Liver function tests are blood tests that can be used to monitor the health of your liver. Ask the doctor what you need to do to prepare. In some cases you may need to avoid food or certain medications before the test.

Liver function tests, also known as liver chemistries, help determine the health of your liver by measuring the levels of proteins, liver enzymes, and bilirubin in your blood. They can also monitor the progression or treatment of an existing disease.

Depending on the test, either higher- or lower-than-typical levels of these enzymes or proteins can indicate a problem with your liver.

Some of the reasons liver function tests may be performed include screening for diseases such as hepatitis, monitoring the side effects of your medications, and examining the severity of liver disease.

In this article, we take a look at when you might need a liver function test, the different types of tests used, and how to interpret results.

A liver function test is often recommended in the following situations:

• to check for damage from liver infections, such as hepatitis B and hepatitis C, especially if it’s suspected you were exposed to a virus that causes hepatitis
• to monitor the side effects of certain medications because some medications are known to affect the liver, including:
  • NSAIDs
  • statins
  • antibiotics
  • antiseizure medications
  • tuberculosis drugs
• if you already have liver disease, to monitor the disease and how well a particular treatment is working
• if you’re experiencing the symptoms of a liver disorder or have a family history of a liver disease, such as fatty liver disease
• if you have certain medical conditions, such as:
  • high triglycerides
  • diabetes
  • high blood pressure
  • anemia
• if you drink alcohol frequently
• if you have gallbladder disease

Certain tests can reflect different aspects of liver function. For example, elevated alanine transaminase and aspartate transaminase disproportional to bilirubin and alkaline phosphatase levels often indicates liver disease.

Liver function tests are used to measure specific enzymes and proteins in your blood.

Having atypical results on any of these liver tests usually requires a follow-up to determine the cause of the atypical characteristics. Even mildly elevated results can be associated with liver disease.

Common liver function tests include:

Alanine transaminase (ALT) test

Alanine transaminase (ALT) is used by your body to metabolize protein. If the liver is damaged or not functioning properly, ALT can be released into the blood. This causes ALT levels to increase. A higher result than what’s typical on this test can be a sign of liver damage.

It’s estimated that about 10 percent of people in the United States have elevated ALT levels.

Aspartate aminotransferase (AST) test

Aspartate aminotransferase (AST) is an enzyme found in several parts of your body, including your:

• heart
• brain
• pancreas
• liver
• muscles

When the liver is damaged, AST can be released into the bloodstream. A high result on an AST test might indicate a problem with the liver or muscles.

Since AST levels aren’t as specific of a marker for liver damage as ALT, it’s usually measured together with ALT to check for liver problems. For example, a high AST:ALT ratio may indicate alcoholic liver disease.

Alkaline phosphatase (ALP) test

Alkaline phosphatase (ALP) is an enzyme found in your bones, bile ducts, and liver. An ALP test is typically ordered in combination with several other tests. An ALP test can be used to evaluate the bile duct system of the liver.

Albumin test

Albumin is the main protein made by your liver. It performs many important bodily functions.

For example, albumin nourishes your tissues and transports hormones, vitamins, and other substances throughout your body. An albumin test measures how well your liver is making this particular protein.

Bilirubin test

Bilirubin is a waste product from the breakdown of red blood cells. It’s ordinarily processed by the liver. It passes through the liver before being excreted through your stool.

A damaged liver can’t properly process bilirubin. This leads to an atypically high level of bilirubin in the blood. Certain inherited diseases can raise bilirubin levels, even when liver function works as expected.

The following table shows what liver function tests may indicate in terms of higher or lower results than typical. Following any liver function test, you should have a discussion with your doctor about your test results and what they mean for you.

Problems with the liver can make a person very sick and can even be life threatening. Approximately 4.5 million adults in the United States have chronic liver disease.

Symptoms of a liver disorder include:

• weakness
• fatigue or loss of energy
• weight loss
• jaundice (yellow skin and eyes)
• fluid collection in the abdomen, known as ascites
• discolored bodily discharge (dark urine or light stools)
• nausea
• vomiting
• diarrhea
• abdominal pain
• atypical bruising or bleeding

Your doctor may order a liver function test if you’re experiencing symptoms of a liver disorder.

Liver function tests can also monitor the progression or treatment of a disease and test for the side effects of certain medications.

Your doctor will give you complete instructions on how to prepare for the blood sample portion of the test.

Certain medications and foods may affect levels of these enzymes and proteins in your blood. Your doctor may ask you to avoid some types of medications, or they may ask you to avoid eating anything for a period of time before the test. Be sure to continue drinking water prior to the test.

You may want to wear a shirt with sleeves that can easily be rolled up to make it easier for the medical expert to collect the blood sample.

You may have your blood drawn in a hospital or at a specialized testing facility. To administer the test:

1. The healthcare technician will clean your skin before the test to decrease the likelihood that any microorganisms on your skin will cause an infection.
2. They’ll likely wrap an elastic strap on your arm. This will help your veins become more visible. They’ll then use a needle to draw samples of blood from your arm.
3. After the draw, the technician will place some gauze and a bandage over the puncture site. Your blood sample will be sent to a laboratory for testing.

Potential risks of a liver function test

Blood draws are routine procedures and rarely cause any serious side effects. However, the risks of giving a blood sample can include:

• bleeding under the skin, or hematoma
• excessive bleeding
• fainting
• infection

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After the test, you can usually resume everyday activities. However, if you feel faint or lightheaded during the blood draw, you should rest before you leave the testing facility.

The results of these tests may not tell your doctor exactly which condition you have or the degree of liver damage, but they might help your doctor determine the next steps. Your doctor will call you with the results or discuss them with you at a follow-up appointment.

In general, if your results indicate a problem with your liver function, your doctor will review your medications and your past medical history to help determine the cause.

If you drink alcohol frequently, then you’ll need to stop drinking it. If your doctor identifies that a medication is causing the elevated liver enzymes, they’ll advise you to stop the medication.

Other diagnostic tests

Your doctor may decide to test you for hepatitis, other infections, or other diseases that can affect the liver. They may also choose to do imaging tests, like an ultrasound or CT scan.

In addition, they may recommend a liver biopsy to evaluate the liver for fibrosis, fatty liver disease, or other liver conditions.

Liver function tests are blood tests used to help determine the health of your liver. Changes in certain levels of proteins or enzymes can alert doctors of potential problems such as liver cancer, fatty liver disease, or hepatitis.

Liver function tests can also help determine if certain medications are damaging your liver or help you monitor the progression of liver disease.

After you get a liver function test, your doctor can help you interpret the results and discuss what the results mean for you. If they suspect you have liver disease, you may need to undergo other tests such as imaging or a liver biopsy.

The Top Causes Of Elevated Liver Enzymes In Dogs

As a pet owner, you want the best for your furry friend. It can be concerning and overwhelming when your dog’s blood work comes back with elevated liver enzymes. However, it’s essential to understand that elevated liver enzymes in dogs are not a disease, but rather a sign that something is going on with the liver. The liver is a vital organ responsible for various metabolic functions, including detoxification and protein synthesis. When the liver is affected, it can lead to an increase in liver enzymes in the blood. There are many possible causes of elevated liver enzymes in dogs, ranging from benign conditions to severe diseases. In this article, we’ll explore the different causes of elevated liver enzymes in dogs so you can have a better understanding of what is going on with your dog.

What are liver enzymes?

Liver enzymes are proteins produced by the liver that help carry out various metabolic functions in the body. These enzymes are released into the bloodstream in small amounts and play a crucial role in breaking down and metabolizing different substances such as drugs, metabolites, and toxins. In dogs, the most commonly measured liver enzymes in blood tests are alanine transaminase (ALT), aspartate transaminase (AST), and alkaline phosphatase (ALP).

ALT and AST are enzymes that are present in the liver cells, and their levels in the blood increase when there is damage or inflammation in the liver. AST is also found in skeletal muscle. ALP, on the other hand, is an enzyme that is present both in the liver and bones. An increase in ALP levels in the blood can indicate liver damage or disease, as well as bone growth secondary to certain medications such as prednisone and phenobarbital.

While it is important to understand that not all elevations in liver enzymes in dogs are suggestive of liver disease, in most cases, elevated liver enzymes in dogs are a sign that there is something going on in the liver, and further diagnostic testing is required to determine the underlying cause. It’s important to keep in mind that elevated liver enzymes in dogs are not a specific diagnosis, but rather an indication that something is affecting the liver.

What causes elevated liver enzymes in dogs?

There are many reasons for high liver enzymes in dogs. Veterinarians typically separate them into two categories: hepatic and extrahepatic.

Hepatic causes of elevated liver enzymes in dogs

Hepatic causes of high liver enzymes in dogs refer to conditions that affect the liver directly, leading to liver damage and subsequent increases in liver enzymes. Some common hepatic causes of elevated liver enzymes in dogs include:

• Hepatitis: Hepatitis refers to inflammation of the liver and can be caused by viral, bacterial, or inflammatory factors.
• Benign nodular hyperplasia: Benign nodular hyperplasia is a condition commonly seen in older dogs in which the liver develops multiple small non-cancerous nodules.
• Drug-induced: Certain drugs, such as steroids (e. g. prednisone) and phenobarbital, can cause elevated liver enzymes in dogs, especially ALP.
• Congenital liver diseases: Certain liver diseases, such as portosystemic liver shunts and copper storage diseases, are inherited and can cause liver enzyme levels to increase.
• Toxins: Certain toxins can induce the activity of liver enzymes in dogs. These can include xylitol, aflatoxins and lead toxicity for example.
• Cholangitis: Cholangitis refers to inflammation of the bile ducts that carry bile from the liver to the small intestine. It can cause liver damage and elevated liver enzymes.
• Cirrhosis: Cirrhosis is a chronic liver disease that leads to scarring and permanent damage to the liver. It can be caused by chronic infections, exposure to toxins, or chronic active hepatitis.
• Liver cancer: Diffuse cancer in the liver, whether malignant or benign, can cause liver enzyme levels to increase. Common cancers that can affect the liver include lymphoma, carcinoma and hemangiosarcoma.

Extrahepatic causes of elevated liver enzymes in dogs

Extrahepatic causes of elevated liver enzymes in dogs refer to conditions outside the liver that can affect liver enzyme levels. Some common extrahepatic causes of elevated liver enzymes in dogs include:

• Pancreatitis: Pancreatitis is inflammation of the pancreas and can cause liver enzyme levels to rise due to inflammation spreading to the liver.
• Diabetes: Dogs with diabetes can have elevated liver enzymes due to the negative metabolic state (subclinical hepatic lipidosis).
• Cushing’s disease: Dogs with Cushing’s disease, or hyperadrenocorticism, can have elevated liver enzymes due to excess steroid production leading to swelling of the liver.
• Heart disease: Right-sided heart disease can cause liver congestion, leading to elevated liver enzyme levels.
• Inflammatory bowel disease: Inflammatory bowel disease (IBD) can cause elevated liver enzyme levels due to inflammation in the gastrointestinal tract.

These illnesses can lead to a reactive/vacuolar hepatopathy, causing an increase in liver enzymes but normally there is no impact on the functioning of the liver.

Do all elevated liver enzymes need to be investigated further?

No, elevated liver enzymes in dogs do not always need to be investigated further. In mild cases of elevated liver enzymes, your veterinarian may recommend periodic blood testing to start trending the values before recommending further testing. Generally speaking, liver enzyme values greater than 2-3 times the upper limit of normal should be investigated as they can indicate a more serious condition. This is also assuming the dog is asymptomatic and there are no abnormalities on its physical exam.

Certain medications such as corticosteroids (prednisone) and phenobarbital will predictably cause elevated liver enzymes in dogs, especially the ALP. In these cases, the elevated liver enzyme values are not indicative of liver disease and will usually resolve with the discontinuation of the medication.

Additionally, young dogs with an elevated ALP may not need to be investigated further as this could be due to skeletal growth and development. Your veterinarian may recommend periodic blood testing to ensure the elevated liver enzyme values do not persist or cause any issues.

Finally, elevated liver enzymes in dogs can be observed as part of an aging process, as normal age-related changes occur to cause increased activity of certain enzymes. Examples include nodular and vacuolar hepatopathy. In this case, your veterinarian may recommend periodic blood testing every 4-6 months.

In conclusion, elevated liver enzymes in dogs can be caused by a variety of conditions, both within and outside the liver. In mild cases of elevated liver enzymes, periodic blood testing may be all that is needed to ensure there are no more serious underlying issues. However, if your dog’s elevated enzyme levels persist or become particularly high (greater than 2-3 times the upper limit of normal), further investigation should be done as soon as possible. Additionally, certain medications such as corticosteroids and phenobarbital will predictably cause elevated values but these usually resolve with discontinuation of the medication. Finally, elevated liver enzymes in young dogs could be due to skeletal growth and development, or part of an aging process. It is important to work with your veterinarian to determine the best course of action for your individual dog.

Interpretation of liver tests and their disorders

04.10.2018

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It is not uncommon for a clinician to examine the liver to assess its functional state. The most commonly used indicators for this are alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (AP) and bilirubin. The measurement of these indicators is traditionally called “liver tests”. Some recommendations of the American College of Gastroenterology (2016) regarding the appointment and interpretation of liver tests are presented in the table.

Hepatocyte damage is usually characterized by a disproportionate increase in AST and ALT against a background of normal or slightly altered ALP; cholestasis, on the contrary, a sharp increase in alkaline phosphatase compared with ALT and AST. As for bilirubin, most of it circulates in the blood in an unconjugated form, and elevated conjugated bilirubin may indicate both hepatocyte damage and cholestasis.

Diagnostic search for laboratory-detected lesions of hepatocytes should include tests for viral hepatitis A, B and C, detection of NAFLD and ALD, screening for hereditary hemochromatosis, autoimmune hepatitis (AIH), Wilson’s disease, α-1-antitrypsin deficiency. The medical history should also be taken into account. With an increase in alkaline phosphatase, it is necessary to diagnose PBC and primary sclerosing cholangitis.

It is important that normal laboratory values ​​are usually defined as the average value in a healthy population ± 2 standard deviations. This definition of the norm covers 95% of people, i.e., in 2.5% of the world’s population, these indicators, by definition, will exceed the norm. The normal levels of ALP and bilirubin differ less in different laboratories, while there is significant variability for ALT.

For example, in one study, 67 laboratories analyzed used an upper limit of normal (ULN) ALT of 31 to 72 U/L. It depends on the equipment of the laboratory, different methods for determining the quantitative indicator of the norm, the characteristics of the population used as healthy.

ALT is a more specific marker of liver damage than AST, but a normal ALT level does not rule out significant liver disease. An increase in AST without a concomitant increase in ALT may indicate damage to the heart or muscles. A borderline increase in AST and/or ALT is considered to be <2×ULN, slight - 2-5×ULN, moderate -5-15 ULN, severe - >15×ULN, and massive – >10,000 IU/L. The diagnostic algorithm at various levels of increase is shown in Figures 1-5.
AP is a member of the family of zinc metalloproteinases that catalyze the hydrolysis of phosphate esters at alkaline pH.

Interestingly, in people with blood type 1 or 2, serum ALP may increase after eating fatty foods, although this metabolic feature is rarely used in practice. The main reasons for the increase in the level of alkaline phosphatase are obstruction of the biliary tract (most often; possibly even in the absence of elevated bilirubin), pregnancy; Also, the level of alkaline phosphatase is increased in children and the elderly, especially in women. With a parallel increase in GGT, it can be concluded that the hepatic cause of the increase in alkaline phosphatase.

Bilirubin, bound to albumin, is formed from the breakdown of old red blood cells and predominantly circulates in unconjugated form. Unconjugated (indirect) bilirubin is not excreted in the urine. In turn, conjugated bilirubin becomes water-soluble and excreted into bile, then converted by intestinal bacteria into urobilinogen, excreted in urine and feces. It is the absence of urobilinogen that gives the feces a discolored appearance in violation of the outflow of bile. Unconjugated bilirubin makes up about 70% of total serum bilirubin.

Determination of bilirubin fractions is especially important when ALT, AST and ALP are in the normal range or slightly changed. If total bilirubin is elevated, mainly due to unconjugated bilirubin, hepatocellular damage is unlikely. An increase in direct bilirubin indicates such lesions or cholestasis.

Liver tests (ALT, AST, ALP, bilirubin) are markers of liver damage, not liver function. Albumin and PTT are indicators of hepatocyte function. Decreased albumin levels (normally ≥3.5 g/dL) usually indicate liver disease lasting ≥3 weeks, although any significant disease can decrease albumin levels due to cytokine exposure. PTT is a more sensitive measure of liver function as it may be elevated in patients with severe liver disease lasting <24 hours.

Of note, albumin, bilirubin, and PTT may be affected by extrahepatic factors. For example, in the presence of vitamin K deficiency and steatorrhea (in the absence of liver disease), cholestasis, or significant hepatocellular dysfunction, PTP lengthens. Treatment with warfarin, heparin bolus administration, disseminated intravascular coagulation syndrome, and hypothermia can also lead to an increase in PTT.

Certain liver diseases

Viral hepatitis B and C

The screening test for chronic hepatitis C is an antibody to the virus with a sensitivity of 92-97%. False positive results are observed in 5% of all cases and in 30% of patients without risk factors. Confirmation of chronic infection is provided by highly sensitive polymerase chain reaction (PCR) with the determination of viral RNA. Individuals with identified RNA should be referred to a specialist for further evaluation of infection and liver fibrosis, and a decision on antiviral therapy.

Acute hepatitis C, accompanied by higher levels of transaminases than chronic, usually occurs without jaundice and other clinical symptoms. The diagnosis of acute hepatitis C can be suspected in the presence of risk factors and confirmed using antibodies to the virus (positive 6-8 weeks after infection) and then by determining the virus RNA by PCR.

Hepatitis B testing should be done in all patients with persistently elevated AST/ALT. Determining the status of infection can be done using three serological tests: HBsAg, indicating the presence of infection; total antibodies to HBcAg, reporting previous exposure to infection or the presence of chronic HBV infection; antibodies to HBsAg, signaling the presence of immunity to this hepatitis that arose as a result of vaccination or a disease transferred in the past.

Chronic infection is confirmed by the presence of HBsAg, antibodies to the core antigen of the virus and / or the determination of viremia using a highly sensitive analysis for the detection of viral DNA. Individuals with chronic hepatitis B should be referred to a hepatologist for further evaluation and a decision on antiviral therapy. The diagnosis of acute hepatitis B is made with a positive test for IgM to HBcAg and the presence of HBsAg. Acute hepatitis B is more often than acute hepatitis C accompanied by clinical symptoms.

NAFLD

NAFLD is an extremely common disease associated with metabolic syndrome. Unlike ALD, there is no unique pattern of changes in ALT and AST for NAFLD, although ALT levels are usually more elevated than AST levels, and levels of both aminotransferases rarely exceed 300 IU/L. Although many individuals with NAFLD suspected of having steatosis on imaging studies may have normal liver tests, the presence of abnormal liver tests indicates a greater likelihood of non-alcoholic steatohepatitis. To establish this diagnosis accurately, a liver biopsy is required, although the role of a non-invasive method for determining the degree of fibrosis and steatosis, elastography, is also increasing.

ABP

Alcohol use is a common cause of elevated liver tests, either alone or in association with chronic liver disease. Specific patterns of changes in liver tests are associated with ALD, in particular the AST:ALT ratio of at least 2:1, and transaminase values ​​rarely exceed 300 IU / L. A further increase in this ratio (3:1, 4:1, etc.) increases the likelihood of ABP. An additional test is the measurement of GGT. All patients with elevated liver tests should be directly asked about alcohol use, recommending that it should be completely discontinued.

Autoimmune liver diseases

Chronic AIH, in which persistently elevated transaminases are noted, can develop in parallel with other autoimmune disorders (hypothyroidism, ulcerative colitis, Sjögren’s syndrome, rheumatoid arthritis, psoriasis). AIH is more common in women than in men (4:1). The characteristic laboratory signs of AIH are the presence of antinuclear antibodies, antismooth muscle antibodies, and less commonly, antirenal and antihepatic microsomal antibodies. The diagnosis of AIH requires histological confirmation with analysis taken from a liver biopsy of a tissue sample.

Drug injuries of the liver

Almost all drugs are associated with at least a minimal risk of elevated liver tests with or without concomitant hepatotoxicity. Among such drugs are antibiotics, antiepileptics, non-steroidal anti-inflammatory drugs, statins, anti-tuberculosis, chemotherapeutic and antiretroviral drugs. It should be noted that although statins are associated with increases in ALT and AST, cases of hepatotoxicity of these agents are rare, even in patients with chronic liver disease. Natural supplements associated with hepatotoxicity include ephedra preparations, green tea extract, and shark cartilage. An online source for information on drug hepatotoxicity is the livertox.nih.gov website. To determine drug damage, treatment should be stopped empirically until ALT/AST normalizes.

PBH

PBC, formerly known as primary biliary cirrhosis, is a rare chronic liver disease that predominantly affects the intralobular bile ducts at a microscopic level. PBC is more common in women than men and is associated with increased fatigue and itching. Laboratory examination reveals elevated alkaline phosphatase with or without elevated bilirubin, as well as the main criterion for diagnosis – a positive analysis for antimitochondrial antibodies (in > 95% of patients).

Other

In patients with jaundice and abdominal pain, a history of previous hepatobiliary disease, including cholelithiasis and inflammatory bowel disease, should be taken. Other extrahepatic causes of abnormal liver function tests include heart failure (congestive hepatopathy), early stages of emphysema, celiac disease, and thyroid disease.

Physical examination findings in patients with abnormal liver tests are usually normal, but some symptoms (jaundice, ascites, splenomegaly, palmar erythema, hepatic encephalopathy) may help confirm the presence of liver disease. In addition, the etiology of the disease can be suspected by specific symptoms. For example, contractures

Dupuytren in combination with an increase in the parotid salivary glands and testicular atrophy may accompany ALD; bronze skin color – hereditary hemochromatosis; severe hepatomegaly – acute viral or alcoholic hepatitis; enlarged nodular liver – a malignant process; right hypochondrium tenderness and a positive Murphy’s sign are hepatobiliary diseases (primarily cholecystitis).

From:
Paul Y. Kwo, Stanley M. Cohen, Joseph K. Lim. ACG Clinical Guideline: Evaluation of Abnormal Liver Chemistries. Am J Gastroenterol advance online publication, 20 December 2016; doi:10.1038/ajg.2016.517

Prepared by Larisa Strilchuk

Medical newspaper “Health of Ukraine 21 stories” No. 17 (438), spring 2018

• Number:
• Medical newspaper “Health of Ukraine 21 stories” No. 17 (438), spring 2018

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When the liver goes wrong: a gastroenterologist named 4 common reasons why ALT and AST are elevated in the blood

• Health

However, the growth of these main “liver” markers in the blood test does not always indicate problems.

April 25, 2022

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A biochemical blood test is considered one of the main ways to find out if the liver copes with the load of “wrong” nutrition, alcohol, and medication. This will be told by such indicators in the analysis as ALT (alanine aminotransferase) and AST (aspartate aminotransferase) – these liver enzymes are among the first to respond to malfunctions of the organ.

– If there is an increase in both ALT and AST, this means that the liver cells are destroyed and the enzymes from them enter the blood. (…) An increase in AST and ALT means that an inflammatory process is taking place in the liver and its cells are being destroyed. If the indicators are above the norm, you need to contact a gastroenterologist, – gastroenterologist Maria Lopatina wrote in her telegram channel, adding that the upper limits of the norm may differ in different laboratories and one must focus on those established where the analysis was taken.

The doctor named the 4 most common causes of increased liver values.

Chronic viral hepatitis

With an increase in ALT and AST in the blood, viral hepatitis B and C are always excluded first. This is very important, as they can be asymptomatic, while destroying the liver. Mandatory tests: HBsAg – hepatitis B and Anti-HCV – hepatitis C.

Non-alcoholic fatty liver disease

When fatty degeneration of liver cells destroys them, ALT and AST in the blood increase and steatohepatitis develops.

Fatty liver disease is suspected if:

• Waist circumference ≥94/≥80 cm in men/women;

• Blood pressure 130/85 mmHg And more, or the person is taking antihypertensive drugs;

• Fasting glucose level of 5.6 mmol/l or more, or the person is taking hypoglycemic drugs;

• Serum triglycerides more than 1.7 mmol/l;

• High-density lipoprotein (HDL) level less than 1.0/1.3 mmol/l in men/women.

Drug-induced liver injury

All drugs that we take by mouth pass through the liver. The more drugs we take, the more likely it is to be damaged. This group includes both herbal preparations and dietary supplements. Liver damage can occur immediately or after several weeks.

Alcohol

According to Russian clinical guidelines, a safe dose for the liver in women is 20 grams of ethanol per day, for men – 40 grams. Regular excess of this dose leads to the development of alcoholic hepatitis and an increase in ALT and AST.

Determining the ethanol content in 100 ml of a drink is very simple: the percentage of alcohol in the drink must be multiplied by 0.8. Thus, 100 ml of 40% vodka contains 40×0.8=32 grams of ethanol, and 100 ml of 12% wine contains 12×0.8=9.6 grams of ethanol.

The doctor specifies that there are other reasons for the increase in ALT and AST in the blood, but these four are the most common.

Read also

When an increase in the indicator is not a cause for alarm

It happens that an increase in the level of “liver” indicators may not be associated with a problem in the work of our main “filter”. According to gastroenterologist Maria Lopatina, this may be the case if only the AST index is elevated.

– AST is found not only in the liver, but also in the heart, muscles, kidneys, brain and pancreas. If AST levels are elevated and ALT is normal, causes that are not related to damage to liver cells should be ruled out. For example, active training for all muscle groups, the doctor clarifies.

But if the liver values ​​are below normal in the blood test, in most cases this is not a cause for serious concern. According to the gastroenterologist, a decrease in their level can occur during pregnancy, starvation and a reduced content of vitamin B6.

What other indicators of a blood test can be used to understand that something is wrong with the liver, read HERE.

Signs of liver problems that can be seen in the mirror

According to doctors, the liver does not hurt in the usual sense of the word, especially at first – the specific symptoms of the disease appear when things have gone too far. As the head of the MIBS outpatient department, gastroenterologist Iyri Alaya said, liver diseases are often accompanied by various digestive disorders:

• Increased gas formation;

• Feeling of fullness in the stomach;

• Rapid satiety after eating;

• Loss of appetite;

• Dryness and bitterness in the mouth;

• Attacks of nausea and vomiting;

• Constipation or diarrhoea.