Parameters of hepatocyte damage


 * Membrane permeability and integrity tests.

Aminotransferases

 * The most sensitive and the fastest telling.

Aspartate aminotrasferase (AST)

 * Transfers an amino group from aspartate to oxoglutarate to form glutamate and oxalacetate.
 * It is present not only in liver cells, but also elsewhere (muscles, kidneys, pancreas and in erythrocytes − during hemolysis the activity of AST in the blood increases).
 * Two forms - one is in mitochondria and the other is in cytosol (35&thinsp;%).
 * S-AST' = 0.66 µcat/l.

Alanine aminotransferase (ALT)

 * Catalyzes the transfer of an amino group from alanine to oxoglutarate, resulting in glutamate and pyruvate.
 * It is in the highest concentration in the liver and kidneys.
 * Present only in the cytoplasm.
 * The half-life of ALT is about 48 hours, the coenzyme is pyridoxal phosphate − when determining enzyme activity, its amount is limiting.
 * That is why we mostly measure turbidity (change in absorbance of NADH).
 * S-ALT' = 0.73 µcat/l.


 * For interpretation, ALT is a sensitive indicator of membrane damage, a greater rise in AST occurs only after cell necrosis.
 * ALT - sensitivity (83&thinsp;%), specificity towards individuals with the disease (84&thinsp;%), AST - about 70&thinsp;%.
 * The so-called de Ritis coefficient − AST/ALT ratio, prognostically more serious at a value greater than 0.7–1.
 * Highest values of transferases - viral hepatitis (prodromal stage - 2x, after two weeks up to 50x increased, around the 8th week they normalize).
 * Rapid rise (approx. 30×) − toxic liver damage.
 * Drug and alcohol intoxication - a slight increase.

Glutamate dehydrogenase (GMD)

 * Relatively specific for the liver (about 10x more in the liver than elsewhere).
 * GMD is a mitochondrial enzyme, also found in muscles, brain and leukocytes.
 * Converts glutamate to oxoglutarate.
 * S-GMD = 0.123&thinsp;cat/l (male); 0.088&thinsp;cat/l (women).


 * A massive increase in GMD is a manifestation of liver necrosis or neoplasia.
 * With obstructions and cholestasis, the values increase up to 10x (induction of enzyme formation in cells).
 * However, the sensitivity is below 50&thinsp;%.

Lactate dehydrogenase (LDH)

 * Lactate dehydrogenase is of rather limited importance for the examination of the liver - it is a cytosolic enzyme that occurs in practically all cells.
 * Half-life of isoenzymes with liver subunits (LDH5 and LDH4) − short half-life (10&thinsp;h).
 * Cardiac subunits predominate - LDH1 and LDH2, which circulate longer.
 * S-LDH = 2.5–7.7 µcat/l.


 * Information on total LDH is non-specific.
 * From liver disorders - the biggest rise in acute liver failure or toxic lesions, also in hepatitis, liver metastases; it tends to be low for obstructions.
 * Examination of isoenzymes by electrophoresis − the most significant is the rise of LDH3 − infectious mononucleosis (from disintegrated monocytes), or pulmonary embolism (from platelets).

Glutathione-S-transferase (GST)

 * Normally penetrates minimally;
 * sensitive indicator;
 * increases mainly with intoxication and drug damage, also with chronic hepatitis and hepatocellular carcinoma.

Related Articles

 * Biochemical tests of the liver
 * Liver function tests