High ALT (SGPT): what it means

What ALT measures

ALT (alanine aminotransferase) is an enzyme found mostly in the liver. Older reports and many labs in India and Pakistan call it SGPT, which is the same test. A small amount in the blood is normal. When liver cells are inflamed or damaged, more ALT leaks out and the level rises. ALT is part of a liver function test (LFT) along with AST (SGOT), GGT, ALP, bilirubin and albumin. A high ALT shows irritation of the liver but does not tell how well the liver is working, which bilirubin, albumin and clotting tests show better.

Common causes

Most high ALT results in adults are mild, under two or three times the upper limit, and come from fatty liver linked to weight, diabetes or high cholesterol. This is now called metabolic dysfunction-associated steatotic liver disease (MASLD), and it is common in South Asia even at a normal weight. Hard exercise can also raise ALT slightly for a few days.

• Fatty liver (MASLD), often with diabetes, prediabetes or a large waist
• Alcohol
• Medicines such as paracetamol in high doses, statins, some antibiotics and herbal remedies
• Viral hepatitis A, B, C or E
• Less common causes such as autoimmune hepatitis, coeliac disease or iron overload

How AST and GGT change the picture

Doctors look at the pattern, not just ALT. When ALT is higher than AST, fatty liver or viral hepatitis is more likely. When AST is about twice ALT or more, alcohol is a common reason, although muscle injury can also raise AST. GGT rises with alcohol, fatty liver and some medicines, and a high GGT with a high ALP points towards a problem with bile flow. Very high ALT, in the hundreds or above 1,000 U/L, suggests sudden liver injury from a virus, a medicine or poor blood flow to the liver.

What usually happens next

For a mild rise with no symptoms, doctors often repeat the test in a few weeks to a few months. Before the repeat it helps to avoid alcohol and hard exercise and to tell your doctor about every medicine, supplement and herbal product you take. Further tests may include hepatitis B and C, a liver ultrasound, blood sugar and lipids. If fatty liver is the cause, gradual weight loss of 5 to 10% of body weight, more activity and less alcohol and sugary drinks often bring ALT back down. Never stop a prescribed medicine without talking to your doctor first.

Questions to ask your doctor

• How high is my ALT compared with the upper limit, and has it changed over time?
• What does the pattern of my ALT, AST and GGT suggest?
• Could any of my medicines, supplements or herbal remedies be raising it?
• Do I need hepatitis tests or a liver ultrasound?
• When should I repeat my liver tests?