According to the World Health Organization (WHO), liver diseases account for around two million deaths globally every year. Viral hepatitis alone caused an estimated 1.3 million deaths in 2022, with about 254 million people living with chronic hepatitis B infection and around 50 million with chronic hepatitis C infection. There is also a rising burden of metabolic dysfunction-associated steatotic liver disease (MASLD), previously known as non-alcoholic fatty liver disease, driven by increasing obesity and diabetes.
An early marker
ALT, also known as serum glutamic-pyruvic transaminase (SGPT), is an enzyme found predominantly inside liver cells. When these cells are damaged or inflamed, ALT leaks into the bloodstream, making it one of the earliest laboratory markers of liver injury.
Arul Prakash, gastroenterologist and hepatologist, SRM Prime Hospitals, Chennai, says ALT is also present in smaller amounts in muscles and the heart. Therefore, an elevated ALT level does not necessarily indicate liver disease and should prompt further evaluation to identify the source of the abnormality.
ALT is one component of the liver function test, which includes other liver enzymes and measures of liver function. Although ALT is a sensitive indicator of ongoing liver injury, patients can still have significant liver disease despite normal ALT values.
ALT testing is performed on a blood sample, with results typically available within a few hours. Although many laboratories consider ALT levels below 40 units per litre as normal, interpretation depends on the patient’s condition. For example, lower thresholds are often applied in people with chronic hepatitis B or C.
People living with MASLD may have normal or only mildly elevated ALT despite having liver disease. In advanced cirrhosis, ALT levels may return to normal because there are too few functioning liver cells left to release the enzyme. As a result, normal ALT values do not exclude significant or advanced liver disease.
Who should be tested?
ALT testing is already part of most comprehensive health check-ups, says Dinesh Jothimani, director of hepatology, Rela Hospital, Chennai. For adults without recognised risk factors, testing once a year is generally adequate. Those at higher risk may benefit from more frequent monitoring, depending on clinical advice.
People living with obesity, diabetes, thyroid disorders, high cholesterol, viral hepatitis, long-term medication use, alcohol consumption, a family history of liver disease or sedentary lifestyles are at greater risk of liver injury and should undergo regular evaluation, he says.
Dr. Jothimani notes that liver enzyme elevation may occur in acute viral hepatitis, alcohol-related liver disease, MASLD, autoimmune hepatitis and chronic liver diseases. However, many patients remain asymptomatic because the liver has a remarkable ability to regenerate and continue functioning despite ongoing damage. Symptoms often appear only in advanced stages of disease, making routine screening particularly valuable.
When ALT is high
An elevated ALT level is not a diagnosis but an indication for further assessment, experts emphasise.
Dr. Prakash says doctors usually perform a complete liver function test, additional blood investigations and, where appropriate, cardiac evaluation to determine the cause. If liver disease is confirmed, treatment depends on the underlying condition. Lifestyle modifications, including reducing alcohol intake, , maintaining a healthy weight, limiting excess saturated fat, refined carbohydrates and sugary foods, and increasing physical activity, remain central to managing metabolic liver disease. Viral hepatitis and autoimmune hepatitis require specific medical treatment.
Experts recommend that people with persistently abnormal ALT levels or suspected liver disease undergo further evaluation under the guidance of a medical professional.
Published – July 31, 2026 10:34 am IST
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