When to worry about ALT levels?

Our content is not intended nor recommended as a substitute for medical advice by your doctor. Use for informational purposes only.

key facts:

  • Any alternation of liver enzymes (particularly ALT) is a cause of concern.
  • The most common cause of the accidental discovery of elevated ALT is a nonalcoholic fatty liver disease (NAFLD).
  • Other causes include alochol abuse, viral hepatitis, medications, and immune-mediated liver diseases.
  • The normal upper levels of ALT differ with age and weight.
  • Children (especially those below the age of 18 months) typically have higher ALT levels.
  • Also, males have higher average ALT levels than females.
  • Therefore, you have to seek medical advice for any ALT levels above the upper limit of normal for your age and sex.

When to worry about ALT Levels?

Any diversion from the normal reference ranges of ALT for your age and sex should be investigated.

It is not normal for your ALT levels to be elevated (even mildly) without knowing the cause.

A minor elevation of the ALT levels can cause significant liver damage if continuous for years. So, always seek medical advice whenever you notice any elevation of your ALT levels.

ALT is a liver enzyme that results from the death and rupture of the liver cell (the hepatocyte).

Under normal circumstances, a physiological (programmed) death of a limited count of liver cells occurs, giving rise to a “normal” level of ALT.

Any increase in ALT levels above the reference range for age and sex means ongoing damage to liver cells. So, You should worry about any  Abnormal levels of ALT.


When to worry about ALT levels (according to your sex and age):

The reference ranges for normal ALT levels also vary from laboratory to laboratory.

Also, Some studies suggest that ALT levels may be slightly higher in people with abdominal obesity. So, these three variants (age, sex, and abdominal obesity) should be considered.

Below, The reference range of normal ALT levels by the famous medical laboratory (LabCorp®).

GenderAge range (years)ALT levels (U/L)
18 or more<33
18 or more.<45

Your doctor should investigate any ALT levels above the above reference ranges.

Should I worry about Mild elevations ofALT (50 to 90 or 100 U/L)?

Mild elevations of liver enzymes (including ALT) are any elevations that are less than five times the upper limit of normal (ULN).

ALT levels such as 60, 70, 80, 90, or 100 U/L are frequently discovered accidentally during routine laboratory investigations. In addition, mild elevations of ALT are often asymptomatic.

The two most common causes of mildly elevated ALT are nonalcoholic fatty liver diseases (NAFLD) and medications.

Mild elevations of ALT  (for example, 50 to 100 U/L) often reflect a chronic liver disease (rather than acute).

Although the damage is not instant, leaving the mild ALT elevation can cause significant liver damage for enough time.

The time it takes for mildly elevated liver enzymes due to chronic inflammation is often years.

Causes of mild to moderate elevations of ALT levels:

The following diseases can cause mild to moderate elevations of liver enzymes (up to 5 times the upper limit of normal ALT):

  • Nonalcoholic fatty liver disease (steatohepatitis).
  • Chronic hepatitis C.
  • Chronic hepatitis B.
  • Liver congestion (in people with heart diseases).
  • Malignant infiltration of the liver.
  • Hemochromatosis.
  • Medications or toxins.
  • Autoimmune hepatitis.
  • Celiac disease.
  • Alochol-related liver injury.
  • Liver cirrhosis.
  • Wilson’s disease.
  • Alpha-1 antitrypsin deficiency.
  • Other viruses such as HEV, EBV, and CMV.


Is minimally elevated ALT levels always mean a liver disease?

The two most important liver enzymes are ALT and AST. They are released from damaged liver cells in the blood, where they can measure.

ALT is more specific as a marker of liver inflammation than ALT, as the liver is its primary source.

AST is not very specific because it is released from other organs (skeletal muscles, brain cells, the heart muscles, and the kidney.

So, ALT is a more specific marker than AST, and even a mild elevation of ALT levels (50 to 100 IU) means that the liver is affected.

How will your doctor evaluate your elevated ALT? (in detail):

The following are the expected approach that your doctor takes to search for the cause of elevated ALT.

Initial Evaluation:

MedicationsDo you have any chronic medications or herbal supplements that can raise your liver enzymes?
AlocholDo you drink alochol? How much? and for how long?
Viral HepatitisYour doctor will do a blood test to screen for Hepatitis B and Hepatitis C virus infection.
Fatty liverYour doctor will order an abdominal US and ALT/AST ratio.

If the initial evaluation is unrevealing:

Autoimmune hepatitisIn females with a history of other autoimmune diseases, your doctor will order blood tests (ANA, Protein electrophoresis, and ASMA).
Hypo- or hyperthyroidismYour doctor may need to test for thyroid malfunction (blood tests).
Celiac diseaseEspecially with diarrhea, your doctor may order a blood test or require an endoscopy.
Wilson’s diseaseA rare disease characterized by excess copper in your body causes liver damage. Evaluation is by a test called serum ceruloplasmin.
Alpha-1 antitrypsin deficiencyrare genetic disease that causes liver damage and lung problems (detected by Alpha-1 antitrypsin level)
Adrenal insufficiencyThe suprarenal gland failure may cause elevations of liver enzymes. Therefore, special tests for cortisol and ACTH level is done to detect the condition).
Muscle diseases.Muscle diseases can cause such problems (particularly elevated AST). So your doctor may order a blood test called (creatine kinase or aldolase).

The last option for unknown causes:

ObservationSometimes, unrecognized drugs, herbal supplements, or transient infections cause the condition. Your doctor may decide to observe and follow up on the ALT level.
Liver biopsyYour doctor may order a biopsy if the elevation persists.