Parameters of hepatocyte damage

Membrane permeability and integrity tests.

Aminotransferases[edit | edit source]

For more information see Aminotransferases.

The most sensitive and the fastest telling.

Aspartate aminotrasferase (AST)[edit | edit source]

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 %).
S-AST' = 0.66 µcat/l.

Transamination reaction.

Alanine aminotransferase (ALT)[edit | edit source]

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.

Transamination reaction.

For interpretation, ALT is a sensitive indicator of membrane damage, a greater rise in AST occurs only after cell necrosis.
ALT - sensitivity (83 %), specificity towards individuals with the disease (84 %), AST - about 70 %.
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)[edit | edit source]

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 cat/l (male); 0.088 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 %.

Lactate dehydrogenase (LDH)[edit | edit source]

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 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)[edit | edit source]

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

Links[edit | edit source]

References[edit | edit source]

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