What is ALT?

Alanine Aminotransferase (ALT), also known as SGPT, is an enzyme found primarily in your liver cells. When liver cells are damaged or inflamed, ALT leaks into the bloodstream, causing elevated levels. It is one of the most specific markers for liver injury.

Why is it Important?

ALT is a key indicator of liver health. Elevated levels can reveal liver damage before symptoms like jaundice or fatigue appear. Because the liver plays a vital role in metabolism, detoxification, and protein synthesis, early detection of liver injury allows timely intervention.

Normal Ranges

Group	Range	Unit
Adult Male	7 – 56	U/L
Adult Female	7 – 45	U/L
Children	7 – 55	U/L

Note: Some laboratories use a stricter upper limit of 35 U/L for males and 25 U/L for females.

What Do Abnormal Results Mean?

Elevated ALT

Common causes include:

Non-alcoholic fatty liver disease (NAFLD) — the most common cause
Alcoholic liver disease
Viral hepatitis (hepatitis A, B, C)
Medications (statins, acetaminophen, antibiotics)
Autoimmune hepatitis
Celiac disease
Obesity and metabolic syndrome

Severity guide:

Mild elevation (< 3× normal): Often fatty liver or medications
Moderate elevation (3–10× normal): Chronic hepatitis, autoimmune
Severe elevation (> 10× normal): Acute viral hepatitis, drug toxicity

Low ALT

Low ALT levels are generally not clinically significant and are considered normal.

When Should You Get Tested?

ALT is included in liver function panels (LFTs) and comprehensive metabolic panels (CMP). Your doctor may order it if you have risk factors for liver disease — heavy alcohol use, obesity, diabetes, hepatitis exposure, or if you are taking medications known to affect the liver.