U-glutamyl transpeptidase in serum

Reference values ​​of the activity of y-glutamyl transpeptidase( GGTP) in serum: in men - 10,4-33,8 IU / l;in women - 8.8-22 IU / liter.

GGTP is a membrane enzyme consisting of hydrophilic and hydrophobic fragments with a molecular mass ranging from 90,000 to 120,000. GGTP is found in significant concentrations in the liver, pancreas, kidney and prostate gland( therefore, in men, the activity of GGTP in the blood serum is approximately50% higher than that of women).In other cells of tissues GGTP is contained in small amounts( excluding cardiomyocytes and myocytes).A small part of the enzyme is in the cytosol, and most of it is associated with the microsome membranes and the cytoplasmic membrane of the cells. In general, the activity of GGTP is high on the membranes of cells possessing high secretory or absorbing capacity, such as biliary epithelial cells,

. Fig. Algorithm for making clinical decisions in establishing the etiology of liver damage based on the activity of alkaline phosphatase

Fig. Algorithm for making clinical decisions in establishing the etiology of liver damage based on the activity of alkaline phosphatase

, the cells of the proximal tubules of the kidney, the acinar tissue of the pancreas and its ducts, the brushing of the intestinal cells. GGTP easily forms complexes with HDL and LDL, with HDL bind to GGTP mainly in intact liver, and LDL - in hepatic jaundice. The half-life of serum GGTP associated with HDL is 20 hours, and the soluble form of GGTP is 9 hours.

The increase in GGTP activity in serum can be due to the following reasons.

■ Increased synthesis as a result of activation of enzymes providing this process with alcohol and drugs.

■ Damage to cell membranes caused by toxic agents, with ischemia and infectious liver damage.

■ The release of the enzyme from binding to cell membranes as a result of the detergent effect of surface-active bile acids in all forms of cholestasis.

The change in the activity of GGTP in serum is of great diagnostic importance in diseases of the liver and hepatobiliary tract. This enzyme is more sensitive to disorders in the liver cells than ALT, AST, alkaline phosphatase, glutamate dehydrogenase( Gldg), etc. The normal activity of this enzyme in bone diseases allows us to establish a source of increased activity of alkaline phosphatase.

GGTP is particularly sensitive to the effect on the liver of long-term alcohol consumption. In alcohol abusers, the activity of GGTP in the blood serum correlates with the amount of alcohol taken. The test is especially valuable for controlling the treatment of alcoholism. Stopping alcohol intake reduces the enzyme activity by approximately 50% within 10 days.

Determination of GGTP activity is used to establish hepatotoxicity;it increases in 90% of cases of liver disease. In most cases, these patients in the blood at the same time increases activity and transaminase. Isolated increase in GGTP activity is observed in 6-20% of patients with pathology of the hepatobiliary system. Increase in GGTP activity more than 3 times cause anticonvulsants, fatty liver and heart failure.

In acute hepatitis, GGTP activity rises earlier than ACT and ALT activity. At the height of the disease, the activity of GGTP is lower( increased 2-5 times) than the activity of aminotransferases, and it normalizes much more slowly. This allows GGTP to be used to monitor the patient's recovery.

The highest activity of GGTP( 5-30 times higher than the reference interval) is observed with intra- and extrahepatic cholestasis. Several smaller values ​​of enzyme activity are recorded in primary liver tumors. In malignant tumors of other localization, the gradual increase in GGTP activity indicates the presence of metastases in the liver. GGTP activity can be used as a marker of pancreatic and prostate cancer, as it reflects remissions and relapses.

It should be noted once again that GGTP is multi-valued in a diagnostic sense. At least 5 processes increase its activity: cytolysis, cholestasis, alcohol intoxication, tumor growth in the liver,

is a drug intoxication. The etiological diversity of mechanisms for enhancing GGTP requires a very careful and thorough assessment of the causes of hyperfermentemia. The detection of high activity of GGTP forces us to look for the cause of this increase. As a "screening" test and a method for monitoring the course of a known pathological process, the GGTP study is literally irreplaceable in terms of clinical significance.

There is no significant increase in GGTP activity in MI, but it increases with pancreatic diseases and, in particular, with diabetes mellitus. Increase in GGTP activity is also observed in infectious mononucleosis.