GPT (ALT, alanine aminotransferase)

GPT – glutamate pyruvate transaminase, internationally ALT (alanine aminotransferase) – is an enzyme found mainly in the cytoplasm of liver cells. Skeletal and heart muscle, kidneys and fat tissue contain much smaller amounts. Among the transaminases, GPT is therefore the value most closely linked to the liver. GPT is measured in serum, usually together with GOT and gamma-GT; the blood sample is taken in a practice.

What GPT (ALT) does in the body

GPT transfers the amino group of the amino acid alanine to α-ketoglutarate, producing pyruvate and glutamate. This reaction is the core of the glucose–alanine cycle: working muscles release nitrogen into the blood in the form of alanine, the liver takes it up, uses GPT to obtain pyruvate for making new glucose and channels the nitrogen into the urea cycle. In this way GPT helps to maintain blood sugar during fasting and exertion and helps to dispose of nitrogen safely. Like GOT, the enzyme needs the active form of vitamin B6 as a helper substance.

Low GPT – what happens in the body?

Low GPT values are usually unremarkable: only a few liver cells are being lost. Because the enzyme depends on active vitamin B6, the measured activity is lower with a vitamin B6 deficiency. Studies have also observed low values in older people with low muscle mass and frailty, as well as in people on dialysis. Whether the low value itself has an effect or merely reflects the general condition has not been clarified.

Raised GPT – what happens in the body?

A raised GPT value shows that liver cells are damaged or their membranes disturbed, so that the enzyme passes into the blood. This occurs with fat accumulation in the liver, which often goes along with overweight and insulin resistance, with liver inflammation caused by viruses, with alcohol consumption, with certain medicines or food supplements and with autoimmune liver diseases. Studies have also observed raised values in untreated coeliac disease. After very intense strength training, GPT from the muscles can rise temporarily. If GPT rises more than GOT, this points rather to damage originating in the cytoplasm of the liver cells.

The interpretation is given in your report.