The Concentration of Cholesterol in the Blood Serum of Normal Man and Its Relation to Age 1

Measurements of blood cholesterol are ordi- narily made for the purpose of comparing the values obtained for the particular individuals, usually prospective or actual patients, with some reference standard. In most cases the reference standard is a value or range of values supposed to represent the "normal" person; sometimes the reference point is a value obtained on some pre- vious occasion from the individual in question. In the latter case, the assumption is implicit that the natural variability of the individual is either negligible or is taken into account in the interpre- tation; in practice this assumption is seldom war- ranted. In the former case, the same assumption enters but an additional assumption is that there is, in fact, a valid reference standard at hand and that this properly defines the normal person or population with which the examinee is to be compared.