What are the normal ranges for AST and ALT liver enzymes. How to interpret high and low AST/ALT results. What symptoms and causes are associated with abnormal AST/ALT levels.

Understanding AST and ALT Liver Enzymes

AST (aspartate aminotransferase) and ALT (alanine aminotransferase) are important liver enzymes that can provide valuable insights into liver health and function. These enzymes are normally found inside liver cells, but when the liver is damaged or inflamed, they can leak into the bloodstream. Measuring AST and ALT levels through blood tests allows doctors to assess liver health and detect potential liver problems.

What are AST and ALT?

AST and ALT are enzymes that play key roles in amino acid metabolism in the liver. While both are found primarily in liver cells, AST is also present in heart, muscle, and kidney cells. ALT is more specific to the liver. When liver cells are damaged, these enzymes are released into the blood, causing elevated levels that can be detected through blood tests.

Normal Ranges for AST and ALT

The normal ranges for AST and ALT can vary slightly between different laboratories and testing methods. However, according to recent guidelines from the American College of Gastroenterology (ACG), the following ranges are considered normal:

• AST normal range for men: Up to 37 U/L
• AST normal range for women: Up to 31 U/L
• ALT normal range for men: Up to 40 U/L
• ALT normal range for women: Up to 35 U/L

It’s important to note that these ranges are more specific and slightly lower than previous guidelines. The ACG now recommends using sex-specific upper limits of normal to improve the accuracy of liver enzyme interpretation.

Interpreting High AST and ALT Results

Elevated AST and ALT levels can indicate liver damage or disease. However, the extent of elevation and the ratio between AST and ALT can provide additional information about the underlying cause.

Mild Elevations (1-3 times upper limit of normal)

Mild elevations in AST and ALT can be caused by various factors, including:

• Fatty liver disease
• Alcohol consumption
• Certain medications
• Obesity
• Mild viral hepatitis

Moderate Elevations (3-10 times upper limit of normal)

Moderate elevations may indicate more significant liver issues, such as:

• Chronic viral hepatitis (B or C)
• Alcoholic liver disease
• Autoimmune hepatitis
• Drug-induced liver injury

Severe Elevations (>10 times upper limit of normal)

Severe elevations in AST and ALT are often associated with acute liver injury, which can be caused by:

• Acute viral hepatitis
• Ischemic liver injury (reduced blood flow to the liver)
• Severe drug-induced liver injury
• Acute biliary obstruction

AST/ALT Ratio and Its Significance

The ratio of AST to ALT can provide additional insights into the underlying cause of liver enzyme elevations. This ratio is particularly useful in distinguishing between alcoholic and non-alcoholic liver disease.

AST/ALT Ratio > 2:1

An AST/ALT ratio greater than 2:1 is often associated with alcoholic liver disease. This occurs because alcohol consumption tends to affect AST levels more significantly than ALT levels.

AST/ALT Ratio < 1:1

When the AST/ALT ratio is less than 1:1, it may indicate non-alcoholic fatty liver disease (NAFLD) or viral hepatitis. In these conditions, ALT levels tend to be higher than AST levels.

Causes of Elevated AST and ALT Levels

There are numerous potential causes for elevated AST and ALT levels. Some of the most common include:

1. Alcohol abuse
2. Non-alcoholic fatty liver disease (NAFLD)
3. Viral hepatitis (hepatitis A, B, C)
4. Drug-induced liver injury
5. Autoimmune hepatitis
6. Hemochromatosis (iron overload)
7. Wilson’s disease (copper accumulation)
8. Cirrhosis
9. Liver cancer
10. Muscular disorders (can cause elevated AST)

Symptoms Associated with Abnormal AST and ALT Levels

Elevated AST and ALT levels themselves do not typically cause symptoms. However, the underlying liver conditions causing these elevations may present with various symptoms, including:

• Fatigue
• Jaundice (yellowing of skin and eyes)
• Abdominal pain or discomfort
• Nausea and vomiting
• Loss of appetite
• Dark urine
• Pale stools
• Itchy skin
• Easy bruising or bleeding

It’s important to note that many liver conditions can be asymptomatic in their early stages, which is why regular liver function tests are crucial for early detection and intervention.

Diagnosis and Further Testing

When elevated AST and ALT levels are detected, healthcare providers typically perform additional tests to determine the underlying cause. These may include:

• Complete blood count (CBC)
• Other liver function tests (e.g., alkaline phosphatase, bilirubin)
• Viral hepatitis serologies
• Autoimmune markers
• Iron studies
• Imaging studies (ultrasound, CT, or MRI of the liver)
• Liver biopsy (in some cases)

The specific tests ordered will depend on the patient’s medical history, risk factors, and the degree of AST and ALT elevation.

Treatment and Management of Elevated AST and ALT

Treatment for elevated AST and ALT levels focuses on addressing the underlying cause. Some general approaches include:

1. Lifestyle modifications:
   • Reducing or eliminating alcohol consumption
   • Adopting a healthy diet
   • Increasing physical activity
   • Weight loss (if overweight or obese)
2. Medication management:
   • Treating viral hepatitis with antiviral medications
   • Managing autoimmune hepatitis with immunosuppressants
   • Discontinuing or modifying medications that may be causing liver injury
3. Treatment of underlying conditions:
   • Managing diabetes and metabolic syndrome
   • Treating hemochromatosis with phlebotomy
   • Managing Wilson’s disease with copper-chelating agents
4. Regular monitoring:
   • Periodic liver function tests to track progress
   • Follow-up imaging studies as needed

The specific treatment plan will be tailored to the individual patient based on the underlying cause of the AST and ALT elevations and any other relevant medical conditions.

Prevention and Liver Health Maintenance

While some causes of elevated AST and ALT levels are not preventable, there are several steps individuals can take to maintain liver health and reduce the risk of liver damage:

• Limit alcohol consumption or abstain completely
• Maintain a healthy weight
• Exercise regularly
• Eat a balanced, nutritious diet
• Avoid unnecessary medications and follow dosage instructions carefully
• Get vaccinated against hepatitis A and B
• Practice safe sex and avoid sharing needles to prevent hepatitis B and C transmission
• Manage chronic conditions like diabetes and high cholesterol
• Avoid exposure to toxins and chemicals that can damage the liver

By adopting these healthy habits and being aware of potential liver risks, individuals can take proactive steps to protect their liver health and potentially prevent abnormal AST and ALT elevations.

Importance of Regular Liver Function Tests

Regular liver function tests, including AST and ALT measurements, are crucial for maintaining overall health and detecting potential liver problems early. These tests are often part of routine health check-ups and can be particularly important for individuals with risk factors for liver disease.

Who Should Get Regular Liver Function Tests?

While liver function tests can benefit everyone, they are especially recommended for:

• People with a family history of liver disease
• Individuals who consume alcohol regularly
• Those with obesity, diabetes, or metabolic syndrome
• People taking medications that can affect the liver
• Individuals with known liver conditions
• People at risk for viral hepatitis

Early detection of abnormal AST and ALT levels can lead to timely intervention and potentially prevent the progression of liver disease. It’s essential to discuss the frequency of liver function tests with a healthcare provider based on individual risk factors and medical history.

Interpreting Test Results

When interpreting AST and ALT test results, it’s important to consider several factors:

1. The specific upper limits of normal used by the testing laboratory
2. The patient’s sex, as normal ranges differ for men and women
3. The presence of other abnormal liver function tests
4. The patient’s medical history and risk factors
5. Any symptoms the patient may be experiencing

Healthcare providers will take all these factors into account when interpreting AST and ALT results and determining the need for further evaluation or treatment.

The Role of AST and ALT in Monitoring Liver Health

AST and ALT levels play a crucial role in monitoring liver health over time, especially for individuals with known liver conditions or those undergoing treatment for liver disease. These enzymes can help healthcare providers:

• Assess the effectiveness of treatments for liver diseases
• Monitor the progression of chronic liver conditions
• Evaluate the impact of lifestyle changes on liver health
• Detect potential liver side effects of medications
• Screen for liver problems in high-risk individuals

Regular monitoring of AST and ALT levels allows for timely adjustments to treatment plans and early intervention if liver health begins to deteriorate.

Fluctuations in AST and ALT Levels

It’s important to note that AST and ALT levels can fluctuate over time, even in healthy individuals. Factors that can cause temporary elevations include:

• Recent strenuous exercise
• Certain medications
• Acute illnesses
• Changes in diet

For this reason, healthcare providers often recommend retesting if mild elevations are detected, especially in the absence of symptoms or other risk factors. Persistent elevations or significant increases in AST and ALT levels warrant further investigation.

Future Directions in Liver Function Testing

As our understanding of liver disease continues to evolve, so do the methods for assessing liver health. Some emerging areas of research and development in liver function testing include:

1. Non-invasive imaging techniques:
   • Transient elastography (FibroScan) for assessing liver fibrosis
   • Magnetic resonance elastography for evaluating liver stiffness
2. Biomarkers:
   • Identification of new biomarkers for specific liver diseases
   • Development of biomarker panels for more accurate diagnosis and staging
3. Genetic testing:
   • Identification of genetic risk factors for liver diseases
   • Personalized medicine approaches based on genetic profiles
4. Artificial intelligence:
   • Machine learning algorithms for interpreting liver function test results
   • Predictive models for disease progression and treatment response

These advancements may lead to more accurate and comprehensive assessments of liver health in the future, potentially improving early detection and treatment of liver diseases.

Conclusion

AST and ALT are vital indicators of liver health, providing valuable insights into potential liver damage and disease. Understanding the normal ranges, interpreting elevated levels, and recognizing the various causes and associated symptoms are crucial for both healthcare providers and patients. Regular monitoring of these liver enzymes, along with other liver function tests, plays a key role in maintaining overall health and detecting liver problems early.

As research continues to advance our understanding of liver disease and diagnostic techniques, the role of AST and ALT in liver health assessment is likely to evolve. However, these enzymes will remain fundamental tools in the evaluation and monitoring of liver function. By staying informed about AST and ALT levels and working closely with healthcare providers, individuals can take proactive steps to protect their liver health and overall well-being.

“Give out with giblets”: this analysis will show that you drink too much alcohol

• Health

The narcologist told you what tests you need to pass in order to understand that you are clearly abusing alcohol. We are talking about four ordinary indicators and one specific.

October 12, 2022

Source:

IStockpoto

Many people believe that a few glasses of dry wine a day or a couple of bottles of beer after work will help to cheer up, relax and is easier to fall asleep. True, doctors have their own opinion on this matter, they warn that it is actually very easy to “cross the line” – regularly “relieving stress”, start abusing alcohol.

Dependence on alcohol develops quite quickly – a person does not notice how he starts drinking more and more. There are indirect signs that alcohol is already taking over you and you are turning from a moderate drinker into a drunkard. For example, for lovers of a foamy drink, there are signs that beer alcoholism is developing. For example, these symptoms will tell you that there is too much alcohol in your life.

Narcologists offer a more accurate method – to pass tests. What indicators in them “will give you away with giblets” and confirm that you are already abusing alcohol? Narcologist explains.

How to understand that a person drinks too much

— Narcologists are often asked this question, — admits narcologist Anna Odintsova. — One way to find out if a person is abusing alcohol is to undergo laboratory tests, take a clinical and biochemical blood test, and another specific test.

Read also

5 important readings

– Normally, its value is 80-100 fL, but the numbers may vary slightly depending on the analyzer used in the laboratory, but the normal range will in any case be indicated on the form with the results analysis,” says Anna Odintsova.

In the biochemical blood test , three indicators can indicate alcohol abuse at once. They characterize the state of the liver:

• AST
  norm for men — up to 37 U/l,
  norm for women — up to 31 U/l.

• ALT

  norm in men — up to 40 U/l,

  norm in women — up to 35 U/l.

• GGT
  norm for men — 10-50 U/l,

  norm for women — 7-32 U/l.

The level of carbohydrate-deficient transferrin (CDT) speaks most precisely about alcohol abuse.

– This indicator is determined during professional medical examinations, when restoring a driver’s license that was withdrawn due to drunk driving. Normal serum CDT content does not exceed 1.2%. Regular alcohol consumption increases CDT levels by 10-15 times!

Read also

It is important to evaluate in a complex

— Many alcohol abusers will have an excess in these five indicators, — sums up the narcologist. — And even if some of the indicators remain normal or close to it, they are are still evaluated in the complex. Each indicator individually may change in other diseases (except for CDT, it evaluates alcohol abuse), but in disputable cases, a consultation with a therapist, an additional specialist, is always prescribed.

The doctor draws attention to the fact that if the “alcohol” tests turn out to be very revealing, no one will force a person to stop drinking — there is no compulsory treatment for alcoholism in narcology. At most, doctors will recommend where and how to seek help.

As for how quickly bad tests can return to normal , the narcologist clarifies that this can only be said in each specific case.

– If you stop drinking, the CDT may decrease to normal within 3 months, other tests – up to 6 months or more. This is an individual process. It all depends on how long and in what volumes a person has been alcoholic. Plus – does a person receive rehabilitation treatment, – says Anna Odintsova.

Text author:Anna Maiskaya

How to interpret ALT, AST, Bilirubin, Alkaline Phosphatase

The American College of Gastroenterology (ACG) has released updated guidelines for blood chemistry tests used to assess liver health

New guidance is targeted at both professionals, as well as primary care physicians.

This document provides specific values ​​for the normal range of alanine aminotransferase (ALT) levels, as well as stepwise screening algorithms for elevations in ALT, aspartic aminotransferase (AST), alkaline phosphatase, and bilirubin. In comparison with the documents of previous editions, the new recommendations contain reduced limits of the norm. Those. previous recommendations have considered upper limit values ​​(URL) as the norm, which can vary significantly between laboratories, ranging from 30-40 international units (IU) per liter in some institutions and up to 70-80 IU/l in others. According to the new guidelines, the normal range for ALT will be 19-25 IU/L for women and 29-33 IU/L for men.

Cirrhosis of the liver. Questions and Answers

The authors noted that they are aware that, due to the decrease in the limits of the norm, many patients will fall into the category with elevated indicators and that this will create certain difficulties for doctors.

However, the authors consider the use of lower starting points justified, pointing out that sometimes even the smallest level of ALT elevation significantly increases the risk of death due to liver disease.

The authors point out that elevated ALT helps identify people with chronic liver diseases such as non-alcoholic fatty liver disease and chronic hepatitis C and B. over time, its level does not return to normal. The authors hope that, over time, practitioners will become accustomed to these new levels, and this will lead to improved liver health for all, as well as general health.

Key recommendations

1. Before starting to evaluate liver function abnormalities, repeat the laboratory panel and/or perform a clarifying test (eg, GGT test if serum alkaline phosphatase is elevated) to confirm that the blood chemistry for liver actually are not normal. (Strong recommendation, very low level of evidence).
2. Chronic hepatitis C testing is done with anti-HCV and confirmation is done with HCV RNA by nucleic acid testing. Risk factors for hepatitis C include a history of intranasal or intravenous drug use, tattoos, piercings, blood transfusions, and high-risk sexual behavior. Also at risk are people born between 1945 and 1965. Testing for acute hepatitis C is done with anti-HCV and HCV RNA by nucleic acid testing. (Strong recommendation, very low level of evidence).
3. Chronic hepatitis B testing is done with HBsAg testing. Testing for acute hepatitis B is associated with HBsAg and anti-HBc IgM.
   The following groups are most at risk: people born in endemic or hyperendemic areas (HBsAg prevalence > 2%), men who have sex with men, ever injecting drug users, dialysis patients, HIV-infected individuals, pregnant women and family members, family members and sexual contacts of HBV-infected persons. (Strong recommendation, very low level of evidence).
4. Testing for acute hepatitis A (IgM HAV) should occur in patients with acute hepatitis and suspected fecal-oral exposure. Acute hepatitis E (IgM HEV) testing should also be done in those returning from endemic areas who test negative for acute hepatitis A, B, and C. (Strong recommendation, very low level of evidence).
5. Patients with elevated BMI and other features of the metabolic syndrome, including diabetes mellitus, overweight or obesity, hyperlipidemia, or hypertension with mild ALT elevations, should undergo ultrasound screening for non-alcoholic fatty liver disease (NAFLD). (Strong recommendation, very low level of evidence).
6. Women consuming more than 140 g of alcohol per week or men consuming more than 210 g per week who have AST>ALT should be considered at risk for alcoholic liver disease and should be advised to stop drinking alcohol. (Strong recommendation, very low level of evidence).
7. All patients with abnormal liver function tests in the absence of acute hepatitis should be tested for hereditary hemochromatosis with iron, transferrin, and serum ferritin levels. HFE mutation analysis should be performed in patients with transferrin ≥45% and/or elevated serum ferritin. (Strong recommendation, very low level of evidence).
8. Patients with abnormal AST and ALT levels, especially those with other autoimmune conditions, should be tested for autoimmune liver disease including ANA, ASMA, and globulin levels. (Strong recommendation, very low level of evidence).
9. Patients with persistently elevated AST and ALT levels, especially those under 55 years of age, should be screened for Wilson’s disease with a serum ceruloplasmin test. If low ceruloplasmin is found, confirmatory testing with a 24-hour urine copper test and slit-lamp eye examination for abnormalities (Kaiser-Fleischer mosaic rings) is recommended. (Strong recommendation, very low level of evidence).
10. Patients with persistently elevated AST or ALT should be screened for alpha-1 antitrypsin deficiency (A1AT) with the alpha-1 antitrypsin phenotype. (Strong recommendation, very low level of evidence).
11. Doctors should ask patients with abnormal kidney tests about their medications and medications, including those they take on their own, without a doctor’s recommendation. It is also worth considering dietary or herbal supplements that may be associated with DILI. (Strong recommendation, very low level of evidence).
12. Liver biopsy may be considered when serological testing and imaging fail to reveal a diagnosis, interpret the condition, or when multiple diagnoses are possible. (Strong recommendation, very low level of evidence).
13. An increase in alkaline phosphatase should be confirmed by an increase in GGT. Given the lack of specificity for liver disease, GGT should not be used as a screening test for underlying liver disease in the absence of other abnormal liver findings. (Strong recommendation, very low level of evidence).
14. Patients with elevated alkaline phosphatase with or without elevated bilirubin should be tested for PBC (formerly called primary biliary cirrhosis) with anti-mitochondrial antibody testing. (Strong recommendation, very low level of evidence).
15. Patients with alkaline phosphatase elevation with or without bilirubin elevation should be tested for PSC by MR cholangiography or ERCP with IgG4. (Strong recommendation, very low level of evidence).
16. In patients with ALT and/or AST levels <5X ULN, laboratory investigations should evaluate the possibility of viral hepatitis B and C, alcoholic and NAFLD, hemochromatosis, Wilson's disease, alpha-1 antitrypsin deficiency, autoimmune hepatitis and consider the possibility of drug poisoning and associated with them liver damage. (Strong recommendation, very low level of evidence).
17. In individuals with an ALT and/or AST level of 5-15X ULN, acute hepatitis A, B, and C should be considered in addition to all etiologies. (Strong recommendation, very low level of evidence).
18. In individuals with ALT and/or AST levels > 15X ULN or massive ALT elevation > 10,000 IU/L, acetaminophen toxicity and ischemic hepatopathy (liver shock) should be considered. (Strong recommendation, very low level of evidence).
19. A patient with acute hepatitis with elevated prothrombin time and/or encephalopathy requires immediate referral to a hepaologist. liver specialist. (Strong recommendation, very low level of evidence).

ALT, alanine aminotransferase; ANA, antinuclear antibodies; ASMA, anti-smooth antibody; AST, aspartate aminotransferase; BMI, body mass index; DILI, drug-induced liver injury; GGT, gamma-glutamyl transferase; HAV, hepatitis A virus; HBc, hepatitis B major antigen; HBsAg, hepatitis B surface antigen; HCV, hepatitis C virus; HEV, hepatitis E virus; HFE, hereditary hemochromatosis; IgM, immunoglobulin M; MR, magnetic resonance; NAFLD, non-alcoholic fatty liver disease; PBC, primary biliary cholangitis; PSC, primary sclerosing cholangitis; ULN, upper limit of normal

Contributors to the guidelines:

Division of Gastroenterology/Hepatology, Department of Medicine, Stanford University School of Medicine Palo Alto, California, USA; Digestive Health Institute, University Hospitals Cleveland Medical Center and Division of Gastroenterology and Liver Disease, Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA; Yale Viral Hepatitis Program, Yale University School of Medicine.