ALT blood test: normal range and what a high result means

An ALT blood test measures alanine aminotransferase, an enzyme held mostly inside liver cells. When those cells are inflamed or injured, ALT leaks into the blood, so it is one of the most direct signs of liver cell stress on a routine panel. Some reports still call it SGPT. A raised ALT is common and is not a diagnosis on its own: what it means depends on how high it is, whether it stays high, and what the other liver markers show.

What ALT measures

ALT is an enzyme, a protein that speeds up chemical reactions inside cells. The liver holds most of the body's supply and other tissues carry much less, so ALT is the more liver-specific of the two transaminases; its partner AST is also plentiful in muscle and heart. Blood normally carries a low level, and more is released when liver cells are damaged. ALT therefore reflects injury happening now, not how well the liver works: bilirubin, albumin and clotting tests speak more to function.

ALT normal range

ALT is reported in units per litre (U/L, also written IU/L). Ranges differ by sex and by laboratory:

Reference	Men	Women
Mayo Clinic Laboratories, age 1 and over	7 to 55 U/L	7 to 45 U/L
IFCC multicentre reference study, adults	9 to 59 U/L	8 to 41 U/L
ACG guideline, upper limit for a healthy adult	29 to 33 U/L	19 to 25 U/L

Laboratory ranges are built from people who count as healthy, some of whom carry undetected fat in the liver, which is thought to push the upper limit too high. The American College of Gastroenterology therefore sets the lower healthy limits in the last row and advises that values above them be assessed. Ranges also vary with method and age, so read your result against the range printed on your own report.

What a high ALT usually points to

ALT and AST raised together, with ALP much less so, is the pattern doctors call hepatitic: stress on liver cells rather than a problem with bile flow. The usual reasons in adults are:

• Fat in the liver, now called metabolic dysfunction-associated steatotic liver disease (MASLD) and formerly non-alcoholic fatty liver disease. It travels with excess weight, type 2 diabetes, raised blood fats and high blood pressure.
• Alcohol, current or past.
• Medicines, herbal products and supplements; MedlinePlus names cholesterol and pain medicines among them.
• Viral hepatitis, such as hepatitis B or C.
• Less common causes, including autoimmune hepatitis, iron overload (haemochromatosis), Wilson's disease and alpha-1 antitrypsin deficiency.

How high ALT goes is not a reliable guide to how serious the cause is. Acute hepatitis A can push it above 1,000 U/L and usually leaves the person well, while hepatitis C can sit with an ALT inside the range, and some people with advanced scarring of the liver have normal enzymes.

What a doctor typically looks at next

The history comes before more tests: alcohol, medicines and supplements, recent illness, hard exercise, and signs of metabolic syndrome such as waist size, blood pressure, blood sugar and blood fats. ALT is then read with AST, the AST / ALT Ratio, GGT, ALP, bilirubin and HbA1c; our article on reading HbA1c, glucose and insulin together covers the metabolic side. If the cause is unclear, British guidance suggests a liver ultrasound and blood tests for viral hepatitis, autoimmune liver disease and iron overload. Where fatty liver is likely, FIB-4, a score built from age, AST, ALT and platelet count, helps decide who needs a scan of liver stiffness.

A low ALT

A low ALT is uncommon. MedlinePlus notes it can be a sign of vitamin B6 deficiency or chronic kidney disease, and a doctor may check further.

What moves ALT

• Hard exercise. One hour of unaccustomed weightlifting raised ALT and AST significantly in 15 healthy men, and both stayed up for at least seven days.
• Weight and metabolic health. Across 17 studies, people with metabolic syndrome had ALT about 7 U/L higher on average.
• Medicines. Statins are a familiar example, though British guidance notes that serious liver injury from them is very rare.
• Age, sex and the menstrual cycle, all listed by MedlinePlus.
• Ramadan fasting. A 2021 review of 20 studies in healthy adults found no clear change in ALT across Ramadan.
• The sample. ALT holds up well in the tube: in a laboratory study, burst red cells (haemolysis) did not distort it until the damage was severe.

Preparing for the test

ALT is usually drawn with tests that need fasting, so labs commonly ask for 10 to 12 hours without food. Mention any heavy training in the week before, recent illness and recent drinking, and list every medicine, supplement and herbal product you take; MedlinePlus advises against stopping any medicine unless your doctor tells you to. Our guide to what to expect from a comprehensive blood test covers the rest.

How Clare's panel handles ALT

Clare's panel includes ALT, measured by the lab. Clare then calculates the AST / ALT Ratio from two lab results: AST divided by ALT. British guidance treats a ratio above 1 as one of the signals that liver scarring may be advanced, even when both enzymes sit inside the range.

ALT and fatty liver in the UAE

Among adults attending Dubai Academic Health Corporation between 2018 and 2023, 49 per cent had at least one MASLD risk factor: type 2 diabetes, obesity with another cardiometabolic risk factor, or a raised ALT. Of those, 21.7 per cent scored at moderate or high risk of advanced scarring on FIB-4, a screening score rather than a diagnosis, as did 15 per cent of people with no risk factor. These were people already using hospital services, so the figures are not a national rate.

Price

ALT is usually sold within a liver function test. When we read public prices on 11 October 2026, a liver function test cost from 89 to 1,100 at six UAE providers. The top figure was a wider package that adds a hepatitis B test; the five standard liver panels ran from 89 to 199. Most listings did not say whether VAT was included, and home collection can add a fee: one lab charged for it on smaller orders.

Related tests

ALT is one part of the Liver function test. Closest to it are Aspartate Aminotransferase (AST), which also comes from muscle; the AST / ALT Ratio; and Gamma-Glutamyl Transferase (GGT), which adds the alcohol and bile duct side.

Why ALT means more over time

One ALT is a snapshot. A mild rise after hard training, a viral illness or a new medicine may settle, and a doctor may repeat the test once that cause has passed. Without such a cause, guidelines advise looking for the reason rather than simply repeating the test: in a large UK study, 84 per cent of abnormal liver tests were still abnormal a month later.

Over years, the direction says more than any single figure. Large studies link a higher ALT with a greater chance of type 2 diabetes later, though the size of that link is uncertain, so an ALT drifting up alongside weight, triglycerides or HbA1c reads differently from one that falls back after a change in habits. When Clare opens, each member's results will sit in one health account, with the trend beside each number.

Clare is opening with a waitlist at clare.health.