What are the normal ranges for liver enzyme tests. How do doctors interpret high or low AST levels. What conditions can affect liver enzyme test results. How are liver function tests performed and what do they reveal about liver health.

The Importance of Liver Enzyme Tests in Assessing Liver Health

Liver enzyme tests play a crucial role in evaluating liver function and detecting potential liver diseases. Among these tests, the aspartate aminotransferase (AST) blood test is particularly significant. AST is an enzyme found in high concentrations in the liver, heart, and muscles, with lower levels present in other tissues. When liver cells are damaged, AST is released into the bloodstream, making it a valuable indicator of liver health.

Understanding the normal range of liver enzymes and interpreting test results accurately is essential for healthcare providers and patients alike. This comprehensive guide delves into the intricacies of liver enzyme tests, focusing on AST and its role in diagnosing and monitoring liver conditions.

Decoding AST: Normal Ranges and What They Mean

The normal range for AST levels in the blood is typically between 8 to 33 U/L (units per liter). However, it’s important to note that normal value ranges may vary slightly among different laboratories due to variations in testing methods or sample types.

Is a result within this range always indicative of good liver health? Not necessarily. While AST levels within the normal range are generally reassuring, they should be interpreted in conjunction with other liver function tests and clinical findings. In some cases, individuals with chronic liver conditions may have AST levels within the normal range, highlighting the importance of comprehensive evaluation.

Factors Influencing AST Levels

• Gender: Males tend to have slightly higher normal ranges for aminotransferase levels
• Ethnicity: Non-white individuals may have marginally higher normal ranges
• Body composition: Obese persons often display elevated baseline levels
• Pregnancy: AST levels can increase during pregnancy
• Exercise: Intense physical activity can temporarily elevate AST levels

Interpreting Elevated AST Levels: Potential Causes and Implications

When AST levels exceed the normal range, it often signals liver dysfunction or damage. However, elevated AST can also result from conditions affecting other organs or tissues where the enzyme is present. Healthcare providers must consider various factors when interpreting high AST results.

What are the common causes of elevated AST levels? Some of the most frequent reasons include:

• Liver cirrhosis (scarring of the liver)
• Acute liver cell death (hepatic necrosis)
• Viral hepatitis (inflammation of the liver due to viral infection)
• Alcoholic liver disease
• Nonalcoholic fatty liver disease (NAFLD)
• Hemochromatosis (iron overload)
• Liver ischemia (reduced blood flow to the liver)
• Liver tumors or cancer
• Certain medications or toxins

It’s crucial to understand that AST elevation is not exclusive to liver conditions. Non-hepatic causes of increased AST levels include:

• Heart attack (myocardial infarction)
• Muscle diseases or trauma
• Pancreatitis (inflammation of the pancreas)
• Mononucleosis
• Deep burns
• Certain medical procedures (e.g., heart surgeries)

The AST/ALT Ratio: A Valuable Diagnostic Tool

While AST levels alone provide valuable information, comparing them to alanine aminotransferase (ALT) levels can offer additional insights. The AST/ALT ratio is particularly useful in differentiating between various liver conditions.

How does the AST/ALT ratio aid in diagnosis? In most types of liver disease, ALT levels typically exceed AST levels. However, in alcoholic liver disease, AST levels are often higher than ALT levels, resulting in an AST/ALT ratio greater than 2:1. This characteristic ratio can help distinguish alcoholic liver disease from other forms of liver damage.

Interpreting AST/ALT Ratios

• AST/ALT < 1: Typical of viral hepatitis and non-alcoholic fatty liver disease
• AST/ALT > 2: Suggestive of alcoholic liver disease
• AST/ALT > 1 but < 2: May indicate cirrhosis or severe liver damage from various causes

Performing the AST Blood Test: What to Expect

The AST blood test is a straightforward procedure that requires a small blood sample. Understanding the process can help alleviate any concerns patients may have about the test.

How is the AST blood test conducted? The process typically involves the following steps:

1. A healthcare professional will clean the area (usually the inside of the elbow or back of the hand) with an antiseptic.
2. An elastic band may be placed around the upper arm to make the vein more prominent.
3. A needle is gently inserted into the vein to draw a small amount of blood.
4. The blood is collected in a vial or tube.
5. The needle is removed, and a small bandage is applied to the puncture site.

Most people experience minimal discomfort during the procedure, typically feeling a brief sting when the needle is inserted. Some individuals may experience slight bruising or throbbing at the site afterward, but these effects usually subside quickly.

Preparing for Liver Function Tests: Do’s and Don’ts

While the AST test itself doesn’t require special preparation, certain factors can influence the results. To ensure accurate test results, patients should follow their healthcare provider’s instructions carefully.

What steps should patients take before liver function tests? Consider the following guidelines:

• Inform your healthcare provider about all medications, supplements, and herbal products you’re taking, as some may affect test results.
• Avoid alcohol consumption for at least 24 hours before the test.
• Fasting may be required for certain liver function tests, but not typically for AST alone. Confirm with your healthcare provider.
• Avoid strenuous exercise for 24 hours before the test, as it can temporarily elevate enzyme levels.

Beyond AST: Other Important Liver Function Tests

While AST is a crucial component of liver function assessment, it’s often part of a broader panel of tests. Understanding these complementary tests can provide a more comprehensive picture of liver health.

What other tests are commonly performed alongside AST? Key liver function tests include:

• Alanine aminotransferase (ALT): Another enzyme that can indicate liver damage
• Alkaline phosphatase (ALP): Elevated levels may suggest bile duct obstruction or certain liver diseases
• Gamma-glutamyl transferase (GGT): Often used to detect bile duct issues and alcohol abuse
• Bilirubin: Elevated levels can indicate liver dysfunction or bile duct obstruction
• Albumin: Low levels may suggest chronic liver disease or malnutrition
• Prothrombin time: Measures blood clotting function, which can be impaired in liver disease

These tests, when interpreted together, provide a comprehensive assessment of liver function and can help diagnose various liver conditions more accurately than any single test alone.

Limitations and Considerations in Liver Enzyme Testing

While liver enzyme tests are invaluable tools in assessing liver health, they have certain limitations that healthcare providers must consider when interpreting results.

What are some key considerations in liver enzyme testing? Important factors to keep in mind include:

• Normal results don’t always rule out liver disease: Some patients with chronic hepatitis or cirrhosis may have normal enzyme levels.
• Enzyme levels can fluctuate: A single abnormal result may not be indicative of a chronic condition.
• Other conditions can affect results: Non-liver related factors, such as muscle damage or heart problems, can influence enzyme levels.
• Medications can impact test results: Certain drugs can cause elevated liver enzymes without necessarily indicating liver damage.
• Timing matters: The stage of liver disease can affect enzyme levels, with late-stage cirrhosis potentially showing lower levels due to reduced liver cell mass.

Healthcare providers must consider these factors alongside the patient’s medical history, physical examination findings, and other diagnostic tests to make accurate diagnoses and treatment decisions.

Special Considerations in Specific Populations

Interpreting liver function tests requires additional care in certain populations:

• Pregnant women: Enzyme levels can be affected by pregnancy-related changes.
• Children: Normal ranges may differ from those in adults.
• Elderly patients: Age-related changes can influence liver function and test results.
• Patients with multiple medical conditions: Coexisting illnesses can complicate result interpretation.

In these cases, healthcare providers may need to adjust their interpretation of test results or perform additional tests to ensure accurate diagnosis and appropriate treatment.

Aspartate aminotransferase (AST) blood test

Medical Tests 

Definition

The aspartate aminotransferase (AST) blood test measures the level of the enzyme AST in the blood.

Alternative Names

Aspartate aminotransferase; Serum glutamic-oxaloacetic transaminase; SGOT

How the Test is Performed

A blood sample is needed.

How to Prepare for the Test

No special preparation is needed.

How the Test will Feel

When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging. Afterward, there may be some throbbing or a slight bruise. This soon goes away.

Why the Test is Performed

AST is an enzyme found in high levels in the liver, heart, and muscles. It is also found in lesser amounts in other tissues. An enzyme is a protein that causes a specific chemical change in the body.

Injury to the liver results in release of AST into the blood.

This test is mainly done along with other tests (such as ALT, ALP, and bilirubin) to diagnose and monitor liver disease.

Normal Results

The normal range is 8 to 33 U/L.

Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or may test different samples. Talk to your health care provider about the meaning of your specific test results.

What Abnormal Results Mean

An increased AST level is often a sign of liver disease. Liver disease is even more likely when the levels of substances checked by other liver blood tests have also increased.

An increased AST level may be due to any of the following:

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• Scarring of the liver (cirrhosis)
• Death of liver tissue
• Heart attack
• Too much iron in the body (hemochromatosis)
• Swollen and inflamed liver (hepatitis)
• Lack of blood flow to the liver (liver ischemia)
• Liver cancer or tumor
• Use of drugs that are toxic to the liver, especially alcohol use
• Mononucleosis (“mono”)
• Muscle disease or trauma
• Swollen and inflamed pancreas (pancreatitis)

AST level may also increase after:

• Burns (deep)
• Heart procedures
• Seizure
• Surgery

Pregnancy and exercise may also cause an increased AST level.

Risks

There is little risk involved with having your blood taken. Veins vary in size from one person to another and from one side of the body to the other. Taking blood from some people may be more difficult than from others.

Risks associated with having blood drawn are slight, but may include:

• Fainting or feeling lightheaded
• Excessive bleeding
• Multiple punctures to locate veins
• Hematoma (blood collecting under the skin)
• Infection (a slight risk any time the skin is broken)

References

Chernecky CC, Berger BJ. Aspartate aminotransferase (AST, aspartate transaminase, SGOT) – serum. In: Chernecky CC, Berger BJ, eds. Laboratory Tests and Diagnostic Procedures. 6th ed. St Louis, MO: Elsevier Saunders; 2013:172-173.

Pincus MR, Tierno PM, Gleeson E, Bowne WB, Bluth MH. Evaluation of liver function. In: McPherson RA, Pincus MR, eds. Henry’s Clinical Diagnosis and Management by Laboratory Methods. 23rd ed. St Louis, MO: Elsevier; 2017:chap 21.

Pratt DS. Liver chemistry and function tests. In: Feldman M, Friedman LS, Brandt LJ, eds. Sleisenger and Fordtran’s Gastrointestinal and Liver Disease. 10th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 73.

Review Date: 01/26/2019

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed physician should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only — they do not constitute endorsements of those other sites. Copyright ©2019 A.D.A.M., Inc., as modified by University of California San Francisco. Any duplication or distribution of the information contained herein is strictly prohibited.

Information developed by A.D.A.M., Inc. regarding tests and test results may not directly correspond with information provided by UCSF Health. Please discuss with your doctor any questions or concerns you may have.

Special Considerations in Interpreting Liver Function Tests

DAVID E. JOHNSTON, M.D.

A number of pitfalls can be encountered in the interpretation of common blood liver function tests. These tests can be normal in patients with chronic hepatitis or cirrhosis. The normal range for aminotransferase levels is slightly higher in males, nonwhites and obese persons. Severe alcoholic hepatitis is sometimes confused with cholecystitis or cholangitis. Conversely, patients who present soon after passing common bile duct stones can be misdiagnosed with acute hepatitis because aminotransferase levels often rise immediately, but alkaline phosphatase and γ-glutamyltransferase levels do not become elevated for several days. Asymptomatic patients with isolated, mild elevation of either the unconjugated bilirubin or the γ-glutamyltransferase value usually do not have liver disease and generally do not require extensive evaluation. Overall hepatic function can be assessed by applying the values for albumin, bilirubin and prothrombin time in the modified Child-Turcotte grading system.

The commonly used liver function tests (LFTs) primarily assess liver injury rather than hepatic function. Indeed, these blood tests may reflect problems arising outside the liver, such as hemolysis (elevated bilirubin level) or bone disease (elevated alkaline phosphatase [AP] level).

Abnormal LFTs often, but not always, indicate that something is wrong with the liver, and they can provide clues to the nature of the problem. However, normal LFTs do not always mean that the liver is normal. Patients with cirrhosis and bleeding esophageal varices can have normal LFTs. Of the routine LFTs, only serum albumin, bilirubin and prothrombin time (PT) provide useful information on how well the liver is functioning.

The general subject of LFTs^1,2 and the differential diagnosis of abnormal LFTs in asymptomatic patients^3–5 have been well reviewed. This article discusses some common pitfalls in the interpretation of LFTs. Hints for interpreting these tests are presented in Table 1.

Situation	Comments
Mildly elevated ALT level (less than 1.5 times normal)	ALT value could be normal for gender, ethnicity or body mass index.
	Consider muscle injury or myopathy.
Alcoholic hepatitis	Laboratory values can appear cholestatic, and symptoms can mimic cholecystitis.
	Minimal elevations of AST and ALT often occur.
AST level greater than 500 U per L	The AST elevation is unlikely to result from alcohol intake alone.
	In a heavy drinker, consider acetaminophen toxicity.
Common bile duct stone	Condition can simulate acute hepatitis
	AST and ALT become elevated immediately, but elevation of AP and GGT is delayed.
Isolated elevation of GGT level	This situation may be induced by alcohol and aromatic medications, usually with no actual liver disease.
Isolated elevation of AP level (asymptomatic patient with normal GGT level)	Consider bone growth or injury, or primary biliary cirrhosis.
	AP level rises in late pregnancy.
Isolated elevation of unconjugated bilirubin level	Consider Gilbert syndrome or hemolysis.
Low albumin level	Low albumin is most often caused by acute or chronic inflammation, urinary loss, severe malnutrition or liver disease; it is sometimes caused by gastrointestinal loss (e. g., colitis or some uncommon small bowel disease).
	Normal values are lower in pregnancy.
Blood ammonia level	Blood ammonia values are not necessarily elevated in patients with hepatic encephalopathy.
	Determination of blood ammonia levels is most useful in patients with altered mental status of new onset or unknown origin.

Markers of Hepatocellular Injury

The most commonly used markers of hepatocyte injury are aspartate aminotransferase (AST, formerly serum glutamic-oxaloacetic transaminase [SGOT]) and alanine aminotransferase (ALT, formerly serum glutamate-pyruvate transaminase [SGPT]). While ALT is cytosolic, AST has both cytosolic and mitochondrial forms.

Hepatocyte necrosis in acute hepatitis, toxic injury or ischemic injury results in the leakage of enzymes into the circulation. However, in chronic liver diseases such as hepatitis C and cirrhosis, the serum ALT level correlates only moderately well with liver inflammation. In hepatitis C, liver cell death occurs by apoptosis (programmed cell death) as well as by necrosis. Hepatocytes dying by apoptosis presumably synthesize less AST and ALT as they wither away. This probably explains why at least one third of patients infected with hepatitis C virus have persistently normal serum ALT levels despite the presence of inflammation on liver biopsy.^6,7 Patients with cirrhosis often have normal or only slightly elevated serum AST and ALT levels. Thus, AST and ALT lack some sensitivity in detecting chronic liver injury. Of course, AST and ALT levels tend to be higher in cirrhotic patients with continuing inflammation or necrosis than in those without continuing liver injury.

As markers of hepatocellular injury, AST and ALT also lack some specificity because they are found in skeletal muscle. Levels of these aminotransferases can rise to several times normal after severe muscular exertion or other muscle injury, as in polymyositis,⁸ or in the presence of hypothyroidism, which can cause mild muscle injury and the release of aminotransferases. In fact, AST and ALT were once used in the diagnosis of myocardial infarction.

Slight AST or ALT elevations (within 1.5 times the upper limits of normal) do not necessarily indicate liver disease. Part of this ambiguity has to do with the fact that unlike the values in many other biochemical tests, serum AST and ALT levels do not follow a normal bell-shaped distribution in the population.⁹ Instead, AST and ALT values have a skewed distribution characterized by a long “tail” at the high end of the scale (Figure 1).⁵ For example, the mean values for ALT are very similar from one population to another, but the degree to which the distribution is skewed varies by gender and ethnicity. The ALT distributions in males and nonwhites (i.e., blacks and Hispanics) tend to have a larger tail at the high end, so that more values fall above the upper limits of normal set for the average population.^10,11

AST and ALT values are higher in obese patients, probably because these persons commonly have fatty livers. ¹² ALT levels have been noted to decline with weight loss.¹³ Depending on the physician’s point of view, the upper limits of normal for AST and ALT levels could be set higher for more obese persons.

Rare individuals have chronically elevated AST levels because of a defect in clearance of the enzyme from the circulation.¹⁴ For both AST and ALT, the average values and upper limits of normal in patients undergoing renal dialysis are about one half of those found in the general population.¹⁵ Mild elevations of ALT or AST in asymptomatic patients can be evaluated efficiently by considering alcohol abuse, hepatitis B, hepatitis C and several other possible diagnoses (Table 2).⁵

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Various liver diseases are associated with typical ranges of AST and ALT levels (Figure 2). ALT levels often rise to several thousand units per liter in patients with acute viral hepatitis. The highest ALT levels—often more than 10,000 U per L—are usually found in patients with acute toxic injury subsequent to, for example, acetaminophen overdose or acute ischemic insult to the liver. AST and ALT levels usually fall rapidly after an acute insult.

Lactate dehydrogenase (LDH) is less specific than AST and ALT as a marker of hepatocyte injury. However, it is worth noting that LDH is disproportionately elevated after an ischemic liver injury.¹⁶

It is especially important to remember that in patients with acute alcoholic hepatitis, the serum AST level is almost never greater than 500 U per L and the serum ALT value is almost never greater than 300 U per L. The reasons for these limits on AST and ALT elevations are not well understood. In typical viral or toxic liver injury, the serum ALT level rises more than the AST value, reflecting the relative amounts of these enzymes in hepatocytes. However, in alcoholic hepatitis, the ratio of AST to ALT is greater than 1 in 90 percent of patients and is usually greater than 2.¹⁷ The higher the AST-to-ALT ratio, the greater the likelihood that alcohol is contributing to the abnormal LFTs. In the absence of alcohol intake, an increased AST-to-ALT ratio is often found in patients with cirrhosis.

The elevated AST-to-ALT ratio in alcoholic liver disease results in part from the depletion of vitamin B₆ (pyridoxine) in chronic alcoholics.¹⁸ ALT and AST both use pyridoxine as a coenzyme, but the synthesis of ALT is more strongly inhibited by pyridoxine deficiency than is the synthesis of AST. Alcohol also causes mitochondrial injury, which releases the mitochondrial isoenzyme of AST.

Patients with alcoholic hepatitis can present with jaundice, abdominal pain, fever and a minimally elevated AST value, thereby leading to a misdiagnosis of cholecystitis. This is a potentially fatal mistake given the high surgical mortality rate in patients with alcoholic hepatitis. ¹⁹

Markers of Cholestasis

Cholestasis (lack of bile flow) results from the blockage of bile ducts or from a disease that impairs bile formation in the liver itself. AP and γ-glutamyltransferase (GGT) levels typically rise to several times the normal level after several days of bile duct obstruction or intrahepatic cholestasis. The highest liver AP elevations—often greater than 1,000 U per L, or more than six times the normal value—are found in diffuse infiltrative diseases of the liver such as infiltrating tumors and fungal infections.

Diagnostic confusion can occur when a patient presents within a few hours after acute bile duct obstruction from a gallstone. In this situation, AST and ALT levels often reach 500 U per L or more in the first hours and then decline, whereas AP and GGT levels can take several days to rise.

Both AP and GGT levels are elevated in about 90 percent of patients with cholestasis.²⁰ The elevation of GGT alone, with no other LFT abnormalities, often results from enzyme induction by alcohol or aromatic medications in the absence of liver disease. The GGT level is often elevated in persons who take three or more alcoholic drinks (45 g of ethanol or more) per day.²¹ Thus, GGT is a useful marker for immoderate alcohol intake. Phenobarbital, phenytoin (Dilantin) and other aromatic drugs typically cause GGT elevations of about twice normal. A mildly elevated GGT level is a typical finding in patients taking anticonvulsants and by itself does not necessarily indicate liver disease.^22,23

Serum AP originates mostly from liver and bone, which produce slightly different forms of the enzyme. The serum AP level rises during the third trimester of pregnancy because of a form of the enzyme produced in the placenta. When serum AP originates from bone, clues to bone disease are often present, such as recent fracture, bone pain or Paget’s disease of the bone (often found in the elderly). Like the GGT value, the AP level can become mildly elevated in patients who are taking phenytoin.^22,23

If the origin of an elevated serum AP level is in doubt, the isoenzymes of AP can be separated by electrophoresis. However, this process is expensive and usually unnecessary because an elevated liver AP value is usually accompanied by an elevated GGT level, an elevated 5′-nucleotidase level and other LFT abnormalities.

In one study,²⁴ isolated AP elevations were evaluated in an unselected group of patients at a Veterans Affairs hospital. Most mild AP elevations (less than 1.5 times normal) resolved within six months, and almost all greater elevations had an evident cause that was found on routine clinical evaluation.

Persistently elevated liver AP values in asymptomatic patients, especially women, can be caused by primary biliary cirrhosis, which is a chronic inflammatory disorder of the small bile ducts. Serum antimitochondrial antibody is positive in almost all of these patients.

Indicators of How Well the Liver Functions

BILIRUBIN

Bilirubin results from the enzymatic breakdown of heme. Unconjugated bilirubin is conjugated with glucuronic acid in hepatocytes to increase its water solubility and is then rapidly transported into bile. The serum conjugated bilirubin level does not become elevated until the liver has lost at least one half of its excretory capacity. Thus, a patient could have obstruction of either the left or right hepatic duct without a rise in the bilirubin level.

Because the secretion of conjugated bilirubin into bile is very rapid in comparison with the conjugation step, healthy persons have almost no detectable conjugated bilirubin in their blood. Liver disease mainly impairs the secretion of conjugated bilirubin into bile. As a result, conjugated bilirubin is rapidly filtered into the urine, where it can be detected by a dipstick test. The finding of bilirubin in urine is a particularly sensitive indicator of the presence of an increased serum conjugated bilirubin level.

In many healthy persons, the serum unconjugated bilirubin is mildly elevated to a concentration of 2 to 3 mg per dL (34 to 51 μmol per L) or slightly higher, especially after a 24-hour fast. If this is the only LFT abnormality and the conjugated bilirubin level and complete blood count are normal, the diagnosis is usually assumed to be Gilbert syndrome, and no further evaluation is required. Gilbert syndrome was recently shown to be related to a variety of partial defects in uridine diphosphate-glucuronosyl transferase, the enzyme that conjugates bilirubin.²⁵

Mild hemolysis, such as that caused by hereditary spherocytosis and other disorders, can also result in elevated unconjugated bilirubin values, but hemolysis is not usually present if the hematocrit and blood smear are normal. The presence of hemolysis can be confirmed by testing other markers, such as haptoglobin, or by measuring the reticulocyte count.

Severe defects in bilirubin transport and conjugation can lead to markedly elevated unconjugated bilirubin levels, which can cause serious neurologic damage (kernicterus) in infants. However, no serious form of liver disease in adults causes elevation of unconjugated bilirubin levels in the blood without also causing elevation of conjugated bilirubin values.

When a patient has prolonged, severe biliary obstruction followed by the restoration of bile flow, the serum bilirubin level often declines rapidly for several days and then slowly returns to normal over a period of weeks. The slow phase of bilirubin clearance results from the presence of delta-bilirubin, a form of bilirubin chemically attached to serum albumin.²⁶ Because albumin has a half-life of three weeks, delta-bilirubin clears much more slowly than bilirubin-glucuronide. Clinical laboratories can measure delta-bilirubin concentrations, but such measurements are usually unnecessary if the physician is aware of the delta-bilirubin phenomenon.

ALBUMIN

Although the serum albumin level can serve as an index of liver synthetic capacity, several factors make albumin concentrations difficult to interpret.²⁷ The liver can synthesize albumin at twice the healthy basal rate and thus partially compensate for decreased synthetic capacity or increased albumin losses. Albumin has a plasma half-life of three weeks; therefore, serum albumin concentrations change slowly in response to alterations in synthesis. Furthermore, because two thirds of the amount of body albumin is located in the extravascular, extracellular space, changes in distribution can alter the serum concentration.

In practice, patients with low serum albumin concentrations and no other LFT abnormalities are likely to have a nonhepatic cause for low albumin, such as proteinuria or an acute or chronic inflammatory state. Albumin synthesis is immediately and severely depressed in inflammatory states such as burns, trauma and sepsis, and it is commonly depressed in patients with active rheumatic disorders or severe end-stage malnutrition. In addition, normal albumin values are lower in pregnancy.

PROTHROMBIN TIME

The liver synthesizes blood clotting factors II, V, VII, IX and X. The prothrombin time (PT) does not become abnormal until more than 80 percent of liver synthetic capacity is lost. This makes PT a relatively insensitive marker of liver dysfunction. However, abnormal PT prolongation may be a sign of serious liver dysfunction. Because factor VII has a short half-life of only about six hours, it is sensitive to rapid changes in liver synthetic function. Thus, PT is very useful for following liver function in patients with acute liver failure.

An elevated PT can result from a vitamin K deficiency. This deficiency usually occurs in patients with chronic cholestasis or fat malabsorption from disease of the pancreas or small bowel. A trial of vitamin K injections (e.g., 5 mg per day administered subcutaneously for three days) is the most practical way to exclude vitamin K deficiency in such patients. The PT should improve within a few days.

BLOOD AMMONIA

Measurement of the blood ammonia concentration is not always useful in patients with known or suspected hepatic encephalopathy. Ammonia contributes to hepatic encephalopathy; however, ammonia concentrations are much higher in the brain than in the blood and therefore do not correlate well.²⁸ Furthermore, ammonia is not the only waste product responsible for encephalopathy. Thus, blood ammonia concentrations show only a mediocre correlation with the level of mental status in patients with liver disease. It is not unusual for the blood ammonia concentration to be normal in a patient who is in a coma from hepatic encephalopathy.

Blood ammonia levels are best measured in arterial blood because venous concentrations can be elevated as a result of muscle metabolism of amino acids. Blood ammonia concentrations are most useful in evaluating patients with stupor or coma of unknown origin. It is not necessary to evaluate blood ammonia levels routinely in patients with known chronic liver disease who are responding to therapy as expected.

Grading Liver Function by Child-Turcotte Class

In communicating among themselves, many physicians use the Child-Turcotte class as modified by Pugh, often termed the “Child class,” to convey information about overall liver function and prognosis (Table 3).²⁹ This grading system can be used to predict overall life expectancy and surgical mortality in patients with cirrhosis and other liver diseases.³⁰

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For elective general abdominal surgery, perioperative mortality is in the neighborhood of several percent for patients who fall into the Child class A, 10 to 20 percent for those in class B and approximately 50 percent for those in class C.³¹ These percentages must be balanced by prognostic considerations when transplantation becomes an option. The presence of cirrhosis by itself is not an indication for liver transplantation, and transplantation is rarely performed in patients who fall into Child class A. For example, the 10-year survival rate is as high as 80 percent in patients with hepatitis C and cirrhosis who have Child class A liver function and no variceal bleeding.³² However, once patients with any type of liver disease fall into the Child-Turcotte class B or class C category, survival is significantly reduced and transplantation should be considered.

what you need to know about your liver health

Contents

• 1 Liver criteria
  • 1. 1 Liver criteria: important information about the condition of a vital organ
  • 1.2 What are liver criteria and why they are important for health
  • 1.3 Functions of the liver and its effects on the body
  • 1.4 Basic indicators of the state of the liver
  • 1.5 Determination of liver criteria through tests and examinations
  • 1.6 Normal values ​​​​of liver criteria and their interpretation
  • 1.7 Influence of liver criteria on health and disease prevention
  • 1.8 Dangerous deviations of liver criteria and their possible consequences
  • 1.9 Factors affecting liver criteria and how to normalize them
  • 1.10 Recommendations for monitoring liver criteria and preventing liver disease
  • 1.11 Importance of regular medical examination for monitoring liver criteria
  • 1.12 Related videos:
  • 1.13 Q&A:
    • • 1.13.0.1 What symptoms may indicate liver problems?
      • 1.13.0.2 What tests will help to find out about the condition of the liver?

Liver criteria (or liver chemistry) are used to assess liver function and identify possible pathologies. Learn what indicators are included in the liver criteria and how to interpret them for liver diagnosis and monitoring.

The liver is one of the most important organs in our body, responsible for many vital functions. It plays an important role in digestion, the processing and disposal of harmful substances, and the production of important proteins and hormones.

However, the liver is also a very vulnerable organ and can be damaged by various factors such as viruses, alcohol, improper diet and drugs. Therefore, it is important to know about the condition of your liver and the features of its work.

There are various methods and criteria to determine how healthy your liver is. One of these criteria is the level of alanine aminotransferase (ALT) in the blood. High ALT levels can be a sign of inflammation or damage to the liver.

It is important to pay attention to your liver and monitor its condition in order to prevent serious consequences. Knowing about liver criteria will help you see your doctor in a timely manner and take the necessary steps to keep your liver healthy.

Liver Criteria: Important information about the condition of a vital organ

The liver is one of the most important organs in our body, with many functions. It plays the role of a filter, cleansing the blood of toxins, is involved in metabolism, synthesizes bile and helps in the digestion of food. The liver also processes drugs and stores vitamins and minerals. It is important to know about the current state of the liver in order to take timely measures to maintain it and prevent the development of diseases.

The most reliable and accurate method for diagnosing liver diseases is a biopsy – taking a small sample of tissue for examination under a microscope. However, this method is not always possible or desirable due to its invasiveness and risks. Therefore, liver criteria based on blood tests and other biochemical parameters can be used to initially assess the state of the liver.

It is important to understand that liver criteria are only indicators and may not fully reflect the condition of the liver. They can be increased not only in liver diseases, but also in other pathologies of the body. Therefore, in case of detection of abnormalities in the liver criteria, you should always consult a doctor for further examination and accurate diagnosis.

What are liver criteria and why are they important for health

Liver criteria are a set of parameters that evaluate the state of the liver and determine the presence or extent of liver disease. These criteria include parameters such as liver enzymes such as alanine aminotransferase (ALT) and aspartate aminotransferase (AST), total and direct bilirubin levels, and albumin and globulin levels.

Liver criteria identify the presence of liver disease in the early stages, when symptoms are not yet apparent. They can also be used to monitor the effectiveness of treatment and estimate disease prevalence. Regular testing for liver criteria allows you to identify possible problems and take steps to prevent or treat them.

Prevention of liver disease includes a healthy lifestyle, including proper nutrition, moderate alcohol consumption, smoking cessation, regular exercise, and avoidance of exposure to toxic substances. It is also important to undergo regular medical examinations and tests, including checking liver criteria, which will allow timely detection and prevention of liver diseases.

The functions of the liver and its effect on the body

The liver is one of the key organs in our body, performing a large number of important functions. Its influence on the work of the whole organism is very great.

One of the main functions of the liver is the processing of food. After digestion, food enters the liver, where it is decomposed into simpler components. Enzymes are produced here that are involved in the breakdown of fats, proteins and carbohydrates, as well as in the synthesis of glucose and glycogen.

The liver is also involved in the regulation of glucose levels in the body. It maintains a normal concentration of sugar in the blood, storing it in the form of glycogen and, conversely, releasing it when its level decreases. This is especially important for maintaining the energy balance in the body.

In addition, the liver is involved in cleansing the body of toxins and slag substances . It filters the blood, removes from it harmful metabolic products, medicines, alcohol and other substances that are incompatible with the vital activity of the body.

The liver is also involved in the formation of bile, which plays an important role in digestion. Bile not only breaks down fats, but also helps to absorb fat-soluble vitamins. It is secreted from the liver into the intestines and is involved in the process of digestion.

By removing toxins and waste products from the liver, synthesizing substances necessary for metabolism and absorption of nutrients, the liver plays a key role in the overall health of the body. Proper nutrition, regular fluid intake, and the absence of organ overload are of great importance so that the liver continues to perform its functions at the proper level.

Liver Health Indicators

Alanine aminotransferase (ALT) is an enzyme found in the liver that helps it process proteins in the body. A high ALT level may indicate liver problems such as hepatitis or cirrhosis.

Aspartate aminotransferase (AST) is another enzyme found in the liver. Elevated AST levels can also be a sign of liver damage, such as hepatitis or cirrhosis.

Gamma-glutamyltransferase (GGT) is an enzyme found in the liver, gallbladder and other organs. Elevated GGT levels may indicate problems with the liver or gallbladder, such as gallstones or alcoholic liver disease.

Albumin is a protein produced in the liver. Low albumin levels can be a sign of liver failure or other liver problems.

Total bilirubin is a pigment produced when red blood cells are broken down and the liver plays a role in its processing. High levels of bilirubin may indicate liver problems such as jaundice or blocked bile ducts.

In addition, there are other indicators such as alkaline phosphatase , alpha-fetoprotein and prothrombin time , which can be used to assess liver function and identify problematic situations. Often these indicators, together with general criteria, help in determining the condition of the liver and identifying any abnormalities in its work.

It is important to note that liver health scores can vary depending on many factors, including age, sex, family history, presence of other diseases, and use of certain medications. Therefore, if you have found abnormalities in your liver parameters, it is recommended to consult a doctor for additional analysis and consultation.

Determination of liver criteria through tests and examinations

Various tests and examinations are carried out to determine the condition of the liver and identify liver criteria. They allow you to evaluate the functionality of the body, identify the presence of possible diseases and determine the degree of their development.

Specialists may also refer to ultrasonography (ultrasound) of the liver to determine liver criteria. With the help of ultrasound, you can assess the size and shape of the liver, identify changes in the structure and the presence of tumors, as well as assess the condition of the biliary tract.

For a more accurate picture, sometimes more complex tests such as magnetic resonance imaging (MRI) or computed tomography (CT) are required. These methods provide detailed images of the liver and surrounding tissues, as well as detect the presence of tumors, cysts, or other formations.

It is important to note that the determination of hepatic criteria through tests and examinations should be carried out under the guidance of qualified specialists such as gastroenterologists or hepatologists. They will be able to evaluate the results and make the correct diagnosis, as well as prescribe the appropriate treatment, if necessary.

Normal values ​​of liver criteria and their interpretation

Many complex biochemical processes take place in the liver, and its condition can be recognized by various indicators, which are called liver criteria. Normal values ​​of these criteria are an important indicator of liver health.

Another important hepatic criterion is Aspartate aminotransferase (AST). Normal AST values ​​also depend on gender and age. In men, they are up to 40 units / l, in women – up to 35 units / l. An increase in AST levels may be associated with various pathologies, including liver diseases.

Creatinine is another indicator that helps assess liver function. The normal value of this indicator lies in the range from 44 to 97 micromol / l for men and from 44 to 80 micromol / l for women. An increase in creatinine levels may indicate a malfunction of the kidneys, which are closely related to the liver.

The concentration of bilirubin in the blood can also serve as an indicator of the state of the liver. Total bilirubin has a normal value of up to 20.5 µmol/L. In the case of an increase in the level of bilirubin, icteric changes occur, which indicate a malfunction of the liver and a violation of the metabolism of bile pigments.

Other important hepatic criteria include total protein, albumin, ammonia, and some other enzymes. The results of the analyzes of these indicators help to diagnose liver diseases and assess its functional state.

Influence of liver criteria on health and disease prevention

The liver plays an important role in the body with many functions, including blood purification, bile production and metabolism. The health of the liver directly affects the general condition of the body, so it is important to monitor the liver criteria and take measures to normalize them.

One of the main indicators of liver function is the level of alanine and aspartate transaminase (ALT and AST) in the blood. An increase in these enzymes may indicate liver damage, which can be caused by various causes, such as viral infections, alcohol or drug damage, fatty liver, and others. Regular monitoring of ALT and AST levels will help identify possible problems and start treatment in a timely manner.

Another important indicator of the state of the liver is the level of total protein and its fractions (albumin and globulin). With a reduced level of total protein, albumin, or an increased level of globulins, the synthetic function of the liver can be impaired. This may be due to nutritional deficiencies, liver disease, or other factors. Regular analysis of total protein and its fractions will help monitor liver function and take corrective measures if necessary.

Prevention of liver diseases includes the following measures: maintaining a healthy lifestyle, avoiding alcohol and smoking, proper nutrition, physical activity, regular preventive examinations by a doctor and adherence to vaccination recommendations. It is also important to avoid contact with toxic substances, take medicines only when prescribed by a doctor, and avoid self-medication. Regular monitoring of liver criteria and timely visits to a doctor will help identify problems in the liver in the early stages and prevent the development of serious diseases.

Dangerous deviations of liver criteria and their possible consequences

The health of the liver plays an important role in the overall health of the body. It performs many functions, including blood filtration, bile production, and metabolism. However, various factors can cause abnormal liver function, which can lead to serious consequences.

One of the main indicators of liver health is the level of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in the blood. Elevated levels of these enzymes may indicate inflammation or damage to the liver. If such deviations are not detected and eliminated in a timely manner, this can lead to the development of cirrhosis of the liver or even cancer.

In addition, elevated levels of bilirubin may also indicate problems with the liver. Bilirubin is a pigment that results from the breakdown of red blood cells in the liver. Elevated levels of this substance may be associated with impaired liver function or obstruction of the biliary tract. In such cases, the person may experience icteric discoloration of the skin and eyes, as well as other symptoms of liver failure.

In addition to these indicators, elevated levels of uric acid in the blood can also indicate problems with the liver. This may be due to metabolic disorders or hepatitis. High levels of uric acid can lead to the development of diseases such as gout.

Thus, regular monitoring of hepatic criteria is an important measure for assessing the condition of the liver and identifying possible abnormalities. If suspicious indicators are found, it is necessary to consult a doctor for further examination and treatment in order to prevent serious health consequences.

Factors affecting hepatic criteria and ways to normalize them

The liver is one of the most important organs of the human body, performing many functions. However, various factors can affect its performance and lead to a violation of hepatic criteria. One of the most common factors is malnutrition. Overeating fatty and fried foods, too much alcohol and sweets can cause liver dysfunction and increase liver criteria.

Diseases such as hepatitis, cirrhosis, and fatty degeneration can also affect liver performance. Inflammation of the liver caused by infection or other factors can lead to impaired organ function and increased hepatic criteria.

One way to normalize liver criteria is proper nutrition. Limiting fatty, fried, and sugary foods can help the liver recover and lower liver criteria.

It should be noted that physical activity and moderate exercise can also have a positive effect on the liver and contribute to its normalization. Regular exercise, walking and other forms of physical activity help strengthen the immune system and improve the general condition of the body, including liver function.

Guidelines for monitoring liver criteria and preventing liver disease

Liver health plays an important role in the overall health of the body, so monitoring its functions and preventing diseases is an integral part of a healthy lifestyle. There are several recommendations to help you keep your liver healthy.

It is important to keep an eye on your diet and stick to a healthy diet. Eating a large amount of fatty, fried and spicy foods can adversely affect the functioning of the liver and lead to the development of diseases. At the same time, it is necessary to increase the consumption of fruits, vegetables, greens, cereals and dairy products, which are rich in vitamins and minerals that positively affect the liver.

It is also important to consume alcohol in moderation to maintain a healthy liver. The systematic use of alcohol can adversely affect liver function, lead to cirrhosis and other serious diseases. It is better to stop drinking alcohol or reduce its level to a minimum.

The third recommendation relates to physical activity. Regular physical activity will help maintain a normal metabolism, strengthen the immune system and improve liver function. It is recommended to play sports or simply increase physical activity by doing morning exercises or walking in the fresh air.

Equally important is the correct use of medicines. Medicines can have a negative effect on the liver, especially when taken for a long time or in excess of doses. You should always strictly follow the instructions for use and consult your doctor if in doubt or side effects.

In conclusion, the control of liver criteria and the prevention of liver disease are important components of a healthy lifestyle. Proper nutrition, moderate alcohol consumption, and regular exercise will help maintain a healthy liver and overall well-being.

The importance of regular medical check-ups to control liver criteria

The liver is one of the most important organs in our body, responsible for purifying the blood, disposing of harmful substances and synthesizing substances necessary for the body to function. In this regard, monitoring the condition of the liver is an integral part of the medical examination.

Liver criteria reflect the functioning of the liver and allow detection of liver disorders at the earliest stages. This requires regular medical examinations, including blood tests for enzyme levels and other indicators related to liver function.

One of the important indicators is the level of alanine aminotransferase (ALT) and aspartate aminotransferase (AST). An increase in these enzymes may indicate the presence of inflammation or damage to the liver. In addition, examinations allow you to assess the level of bilirubin, which is associated with the formation and excretion of bile, and may indicate abnormalities in the liver.

Regular medical examination allows not only to identify problems with the liver, but also to take timely measures to correct them. If abnormalities are found, the doctor may prescribe the necessary treatment, recommend diet and lifestyle changes to maintain the functionality and health of the liver. In addition, regular monitoring of indicators allows you to track the effectiveness of the treatment and adjust it if necessary.

Thus, regular medical examination and monitoring of liver criteria are an important part of a healthy lifestyle. They allow you to detect liver dysfunction at an early stage and prevent the development of serious diseases. Therefore, it is necessary not to forget about your health and regularly consult a doctor for a preventive examination.

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Q&A:

What symptoms may indicate liver problems?

Symptoms of liver problems may include jaundice, liver enlargement, alcohol consumption, loss of appetite, fatigue, and depression.

What tests will help to find out about the condition of the liver?

Common liver tests include alanine aminotransferase (ALT), aspartate aminotransferase (AST), bilirubin, and hepatitis viruses.

What is the normal range of liver enzymes?

Normal liver enzyme levels for adult males are 7 to 55 units per liter of alanine aminotransferase, or ALT, and 8 to 48 units per liter of aspartate aminotransferase, or AST, notes the Mayo Clinic. The normal level of alkaline phosphatase, or ALP, is between 45 and 115 units per litre.

Normal ranges for ALT, AST and ALP vary slightly for women and children, and values ​​for men vary with diet and medications.

Liver function tests are usually done along with kidney function tests and electrolyte measurements, says eMedicineHealth. Measurements are taken to determine an individual’s risk of developing liver disease or to check the progression of current liver disease, the Mayo Clinic notes.

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