Low Liver Enzymes: what does it mean?

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Key facts about low liver enzymes:

  • Accidental low liver enzymes (ALT, AST, ALP, or GGT) can be found in young and healthy individuals.
  • Low liver enzymes are generally not a cause of concern.
  • Low liver enzymes are common among seniors, smokers, alcoholics, patients with chronic kidney diseases, and women who take OCPs.
  • In patients with advanced liver cirrhosis (with jaundice, ascites, and lower limb swelling), Low liver enzymes are a sign that the liver is depleted (in the terminal stages).
  • No treatment is needed for accidentally discovered low liver enzymes in people without significant liver diseases.

1. What do low liver enzymes mean?

You may come over liver enzyme levels during routine laboratory investigations to find them very low.

Low liver enzymes is a term that describes below-range values of liver enzymes (according to your specific laboratory).

The same cut-off levels for low liver enzymes differ from hospital to hospital. Some labs consider very low levels of liver enzymes normal (the lower normal range of liver enzymes is zero).

So, there are no universal cut-off levels below which we say your liver enzymes are low. However, significantly low levels are considered with ALT are below 10 or 7.

Refer to the lower reference ranges provided by the laboratory or the hospital which performed the test.

For example, the table below shows the ranges below your liver enzymes are considered low (reference).

Liver enzyme

Low level in men (U/L)

Low level in women (U/L)

[*] ALT: Alanine aminotransferase.

[**] AST: Aspartate aminotransferase.

[***] ALP: Alkaline phosphatase.

[****] GGT: Gamma-glutamyl transferase.

ALT, AST, ALP, and GGT are the most commonly used liver enzymes for assessing your liver.

During a routine investigation, you may notice low or very low levels (close to zero) of liver enzymes. In most cases, the low levels of liver enzymes are not a cause of concern.

And you don’t have to be anxious about them. Continue reading below to understand why.

What are the possible causes of low liver enzymes?

Low liver enzymes are occasionally found during routine laboratory investigations. However, they are generally not a cause of concern if you don’t have advanced liver or kidney disease.

Understanding the value of liver enzymes levels:

Liver enzymes are complex chemical molecules found inside the cells of your liver and biliary system.

When a liver cell dies, part of the cell contents is released into the blood, including liver enzymes.

So, the detection of this liver enzyme reflects the rate at which liver cells die.

Under normal conditions, your liver cells undergo a continuous process of wear and tear. During which, some cells age and die while other cells are born.

The continuous wear and tear process are why we all have baseline levels of liver enzymes.

A high liver enzyme often means ongoing excess damage to the liver cells.

Low liver enzymes mean either low levels of liver cell turnover or the depletion of the liver cells (as with end-stage liver disease).

The possible causes of low liver enzymes differ according to the condition of your liver.

A. Normal variant.

Low liver enzymes (ALT and AST levels below 20 or even below 10 U/L) are normal findings in some people.

The reason behind that is how the reference ranges for liver enzymes are calculated. Statisticians often calculate the range based on the levels in a large number of healthy people.

Then, they calculate the upper and lower levels of ranges that include 95% of people. This means a 5 % chance that your levels may be a bit lower or higher.

So, low levels of your liver enzymes often don’t have significance. Instead, doctors are often more concerned with high levels of liver enzymes.

So, there is no need to worry about low levels of liver enzymes. In most cases, there is no underlying disease or health condition causing the low levels of liver enzymes (just normal variation).

Some laboratories consider any above zero levels of ALT or AST normal.

B. Aging liver (in the elderly).

In the elderly (seniors) below range may reflect the aging of the liver. The aged liver will not have enough wear and tear process.

Studies found that the more profound the decline in ALT and AST liver enzyme levels may be associated with a higher risk of mortality than those with normal or slightly high levels.

For example, One study followed a sample of 455 elderly (above 70) for twelve years. The study found a slightly increased risk of death in males with low ALT levels.

Another large meta-analysis study found the same association between extremely low liver enzyme levels (ALT below 5 U/L) and long-term mortality risk in seniors.

C. Vitamin B6 deficiency.

For ALT to function, it needs adequate amounts of vitamin B6. Therefore, low levels of the liver enzyme ALT may indicate vitamin B6 deficiency.

However, B6 deficiency is rare in healthy people. The deficiency is relatively common in patients with alcohol abuse, kidney disease, liver cirrhosis, and seniors.

Supplementation of vitamin B6 may correct the very low levels of liver enzymes.

Symptoms of vitamin B6 deficiency include:

  • Inflammation of the skin (dermatitis).
  • Skin rashes (red, scaly, and greasy rashes).
  • Lip cracks and soreness.
  • Red, glazed tongue.
  • Weak immunity (recurrent infections).
  • Mood changes (depression, anxiety, irritability, or poor tolerance to pain).
  • Generalized fatigue and weakness.
  • Nerve damage (tingling and numbness in hands and feet.
  • Severe cases may cause fits (seizures).

Learn More.

D. End-stage liver diseases.

In patients with end-stage liver cirrhosis or those with severe acute liver failure, The low levels of liver enzymes may indicate depletion of the liver cells.

It is a sign that liver reserve is decreasing. Therefore, people with low liver enzymes with cirrhosis may have a poorer prognosis than those with normal liver enzymes.

E. Others

1. Smoking.

Some studies found a link between smoking and lower liver enzymes (particularly ALT levels). However, the link is weak, and the results are inconsistent.

2. Regular exercise.

Young adults who exercise regularly may have lower levels of liver enzymes (reference). Both aerobic and strength exercise can be associated with lower levels of ALT and AST.

3. Chronic kidney diseases.

People who have kidney impairment or end-stage renal disease often have lower levels of liver enzymes (particularly ALT). The effect may be due to the associated vitamin B6.

4. Birth control.

Several studies found that oral contraceptive pills (OCPs) or hormonal replacement therapy is associated with low liver enzyme levels (particularly ALT).

MORE: Low AST Levels: Should you worry?


What are the symptoms of low liver enzymes?

Low liver enzymes are often asymptomatic in most people. However, In rare cases, low liver enzymes may reflect another disease such as vitamin B6 deficiency which causes skin rashes, lip cracking, tongue soreness, and fatigue.

Does pregnancy cause low liver enzymes?

Pregnancy doesn’t lead to low liver enzymes (ALT and AST) in most cases. However, Other liver tests may be low during pregnancy§, such as total and direct bilirubin. In addition, other liver enzymes may increase during pregnancy, such as alkaline phosphatase (ALP).

When should I worry about low liver enzymes?

In most cases, Low liver enzymes (ALT, AST, ALP, or GGT) are not a cause of concern. They are considered normal in people without end-stage liver disease.

You should see your doctor about low liver enzymes when you have other signs and symptoms of vitamin B6 deficiency (skin rashes, cracked lips, sore tongue, mood changes). Or if you have end-stage liver or kidney disease.

What is the treatment for low liver enzymes?

In healthy people without liver or kidney diseases, No treatment is needed for low liver enzymes.  In most cases, low liver enzymes are not considered a disease.

Consult your doctor about the need for vitamin B6 supplementation for low liver enzymes if you are an alcoholic, older than 70, or have chronic kidney disease.

Do liver enzymes mean liver problems?

Low liver enzymes in a young, asymptomatic individual don’t mean you have liver disease. Only in patients with end-stage liver cirrhosis or liver failure low liver enzymes may mean your liver cells are depleted.

Also, low liver enzymes in seniors may indicate that their liver is aging. It is not a disease; It is just a sign of aging. No treatment is needed in such cases.