Combined with transaminases, the detection of alcohol abuse becomes more secure. AST levels also increase in MI, heart failure, muscle injury, CNS disease, and other nonhepatic disorders. Despite some nonspecificity, high levels indicate liver cell injury. The magnitude of the elevation has no prognostic value and does not correlate with the degree of liver damage. AST is reliable and part of routine screening for liver disease.
Many exceptions limit the practicality of the ratio.
It might be quite high with malignancies involving the liver. Its serum concentration is determined by the relative rates of its synthesis and degradation or loss, by its distribution between the intra- and extravascular beds, and by plasma volume. Its biologic half-life is about 20 days, meaning that serum levels will not reflect hepatocellular function in acute liver disease. Alcoholism and malnutrition also depress albumin synthesis. Vitamin K is necessary for prothrombin and factors VII and X production in an active form.