Serum cholesterol measurement; hazards in clinical interpretation.

The conclusions that can be drawn from determinations of total serum cholesterol must take into account the varying results obtained by the use of different methods in different laboratories, the discrepancies to be expected between samples taken on the same day, and the physiological variations in a given individual over periods of weeks or months. Duplicate serums from three patients who had had myocardial infarction were analyzed in five different laboratories, one of which used two methods. Not only were the results consistently higher in some laboratories than in others, but the rankorder of the results varied also.The discrepancies were such as to necessitate great caution in drawing inferences regarding diagnosis and treatment from a single cholesterol determination. In assessing the patient's progress on therapy, to be of significance a cholesterol level checked but once after therapy must decrease about 100 mg. per 100 cc. or else there must be a lesser decrease of about 60 mg. per 100 cc. which is consistently maintained.