Pitfalls in the interpretation of blood chemistry results
Apparently abnormal blood chemistry results may be caused by many factors other than disease. Incorrect specimen collection with excessive venous stasis and haemolysis, or undue delay in separating cells from serum can affect a number of tests. Medication may also influence results, notably the protein-bound iodine, as may procedures such as rectal examination and intravenous fluid administration. Interpretation of results requires full clinical information as well as a knowledge of the time of day that the specimen was collected. Normal ranges should be used intelligently and may vary with age, sex, race and diet. There is no clearcut distinction between values found in healthy persons and those with a particular disease. Difference between laboratories makes it imperative that results be compared only with the normal range issued by the laboratory performing the test.