Reference distributions for immunoglobulins A, G, and M: a comparison of a large cohort to the world's literature.

Clinical interpretation of immunoglobulin measurements requires accurate and precise assays and widely accepted reference preparations, as well as reliable age- and gender-specific reference ranges. This last requirement, the topic of numerous publications, has not been addressed adequately. By a combination of computerized and hand searching of the literature from 1961 to 1997, we identified 109 publications presenting IgA, IgG, and/or IgM reference data in healthy individuals. After eliminating studies that lacked appropriate clinical, statistical, or reference material information, data from the 17 acceptable studies were converted to a common reference material, CRM 470/RPPHS. When median levels from our recently published large cohort study are superimposed on these published medians, they fall within the ranges of reported medians. The widths of published 95 percentile reference ranges (where each individual's health was verified) were also found to agree closely with the reference range widths found in our data (where inclusion was based on the reported diagnosis). The current combined study of narrowly applied reference ranges validates our recently published age- and gender-specific reference data for immunoglobulinsA, G, and M. Those new data can now be considered as a source of reliable reference ranges to be used by laboratories when interpreting immunoglobulin measurements.