Estimation of Normal Ranges from a Controlled Sample Survey. I. Sexand Age-Related Influence on the SMA 12/60 Screening Group of Tests

A panel of 13 clinical chemical tests was performed on sera from 1419 clinically normal adults, utilizing the SMA 12/60 AutoAnalyzer, to obtain practical normal range estimates by nonparametric statistical methods. Serum samples were obtained over a period of 14 months from eight geographic areas of the United States. Normal range estimates are derived for the entire group surveyed, for subgroups of males and females, and for various age categories within each of the two subgroups. For each panel test, sexand age-related variation is assessed by using nonparametric statistical tests for identity of normal-range endpoints. Derived normal ranges that are practical for clinical laboratory usage are proposed. Finally, a measure of validity of our estimates of normal range is applied.