Biomarkers

ALT (Alanine Aminotransferase)

Alanine aminotransferase (ALT) is a key enzyme found primarily in the liver. It plays an essential role in converting proteins into energy for liver cells. High levels of ALT in the blood can indicate liver damage or other health conditions, making it crucial to understand what your ALT levels mean and to know when to take a test.

What is ALT?

ALT is an enzyme that helps turn proteins into energy. Although it is mostly active in the liver, smaller amounts are present in the kidneys, heart, muscles, and pancreas. Normal levels of ALT in the blood are generally low. However, when liver cells are damaged, they release ALT into the bloodstream, causing high levels.

Monitoring ALT levels is essential for assessing liver health. Abnormally high or low levels can indicate health conditions ranging from minor liver irritations to serious conditions like liver cancer.

When should you recommend an ALT test?

An ALT test is often prescribed when there are symptoms that suggest liver disease, including:

  • Tiredness and weakness.
  • Itchy skin.
  • Appetite loss.
  • Dark urine.
  • Pale stools.
  • Abdominal pain, nausea, vomiting.
  • Jaundice (yellowing of the skin or eyes)
  • Family history of liver disease.
  • Excessive alcohol consumption.
  • Use of drugs or medications that affect the liver.
  • Obesity, diabetes, or metabolic syndrome.

How does an ALT test work?

ALT is measured using a blood test, which is often included in a comprehensive metabolic panel (CMP).

To ensure accurate results, follow these preparation steps:

  • Fasting : Do not eat for 8 hours before the test (you can drink water).
  • Avoid alcohol : Do not consume alcohol 24 hours before the test.
  • Stress Management : Avoid physical effort or emotional stress 30 minutes before the test.
  • No tobacco : Do not smoke 30 minutes before the test.

What are normal ALT levels?

ALT levels can vary by age, gender, and overall health. Here are the standard ranges:

Children:

  • Boys (over 1 year old) : 7—55 UI/L.
  • Girls (over 1 year old) : 7—45 UI/L.

Pregnant women:

  • 1st quarter : 3—30 UI/L.
  • 2nd quarter : 2—3 UI/L.
  • 3rd quarter : 2—25 UI/L.

Adults:

  • General range : 10—30 UI/L.

Note: The units of measurement and the normal ranges may vary depending on the laboratory and the methods used.

What do abnormal ALT levels mean?

High ALT levels

High levels of ALT are often associated with liver conditions, but they can also indicate other health conditions:

  • Heat stroke : May cause liver damage.
  • Destruction of red blood cells : Releases ALT into the blood.
  • Muscle injuries : Serious injuries like rhabdomyolysis can increase ALT.
  • Drug overdose (paracetamol, for example): Toxic to the liver.
  • Excess vitamin A : May cause liver toxicity.
  • Acute viral hepatitis : Infections like Hepatitis A, B, or C.
  • Chronic liver diseases : Chronic hepatitis, hepatic steatosis.
  • Bile duct blockages : Obstructions can cause ALT to leak into the bloodstream.
  • Heart disease : Heart failure or heart attack.
  • Cirrhosis : Advanced stage of liver disease.
  • Liver cancers : May cause significantly high levels.
  • Alcohol abuse : Severe liver damage.
  • Epstein-Barr virus : Causes mononucleosis.
  • Medications : Some treatments (statins, aspirin) can stress the liver.

Recommendations for Managing High Levels :

  1. Consult a health professional : Identify the underlying cause.
  2. Limit alcohol consumption : Reduce or eliminate alcohol to avoid worsening the damage.
  3. Monitor medications : Avoid medications that are known to affect the liver without medical advice.
  4. Adopt a healthy diet : Eat fruits, vegetables, and whole grains.
  5. Stay hydrated : Drinking enough water helps eliminate toxins.
  6. Exercise regularly : Improves overall liver health.
  7. Avoid excess vitamin A : Do not exceed the recommended daily intake.

Low ALT levels

Although rare, low ALT levels can also indicate some problems:

  • Vitamin B6 deficiency : Essential for the production of ALT.
  • Smoking : May cause a drop in ALT.
  • Chronic kidney disease : May reduce ALT levels.
  • Heart diseases : Some heart conditions may be linked to a decrease in ALT.
  • Aging : ALT production may decrease with age.

Recommendations for Managing Low Levels :

  1. Increase vitamin B6 intake : Eat poultry, fish, potatoes, and non-acidic fruits.
  2. Quit smoking : Helps improve liver health.
  3. Monitoring kidney health : Consult a physician to manage any underlying conditions.
  4. Living a heart-healthy lifestyle : Balanced diet, regular exercise, stress management.

Which Specialist To Consult?

In case of abnormal ALT levels, consult:

  • Hepatologist : For liver disorders.
  • Cardiologist : If heart problems are suspected.

Monitoring your ALT levels and taking preventative measures can help protect your liver and overall health.