A Comparison of Some Methods of Cholesterol Measurement.

Five referee sera were analyzed for total cholesterol at several laboratories by up to 10 different methods or modifications. Results by any method varied less within a single laboratory than among laboratories, although the ranges of replicate analyses reported differed considerably. Those methods including procedures for saponification with potassium hydroxide and some isolation of cholesterol from other chromogens by digitonin precipitation or re-extraction into petroleum ether, in general, yielded results somewhat lower than those obtained by methods which did not include these procedures.