Serum trypsin inhibitory capacity and Pi phenotypes. I. Methods and control values.

Serum trypsin inhibitory capacity determinations are of considerable value in detecting genetically determined types of obstructive pulmonary disease and hepatic disease. These determinations must frequently be followed by determination of protease inhibitor (Pi) phenotype in order to confirm the diagnosis. Piphenotyping has been a specialized and time-consuming procedure, and suggested improvements in the methodology and technics may make it more generally applicable as a clinical laboratory procedure. The prevalence of phenotypes other than MM in a group of 700 control sera from blood donors is reported as a baseline to evaluate typically American populations of mixed ethnic and racial characteristics. There are suggestive differences in prevalences of S and Z genes relating to ethnic stock and racial groups. It is important when comparing the prevalences of S and Z genes in diseasedpopulations to use control groups of similar ethnic and racial compositions. Pi phenotyping is a necessary laboratory procedure in the diagnosis of certain forms of genetically determined chronic obstructive pulmonary disease and hepatic disease. The distributions of all serum protease inhibitory capacity values and those for S and Z Pi phenotypes are shown.