In the last decade, measurement of the levels of certain serum enzymes has come to be an important adjunct to medical practice. Diagnostic significance is attached to the rise of serum acid phosphatase in carcinoma of the prostate, elevation of serum glutamic oxaloacetic transaminase in acute myocardial infarction, the very low levels of cholinesterase in liver disease and high levels in hyperthyroidism, the extremely low level of serum alkaline phosphatase in hypophosphatasia, and changes in serum lactic dehydrogenase activity in certain cases of carcinoma. It has been shown that neither age nor sex influences enzyme levels and that those individuals with nonmalignant tumors (positive controls) do not differ significantly in their enzyme patterns from healthy hospital personnel (negative controls). Patients with various malignant tumors, however, reveal a pattern of change involving a number of serum enzymes which tend to be characteristic of a tumor type.1-3
In another study4