Comparison of three methods for 17 alpha-hydroxyprogesterone

We compared the performance of three 17 alpha-hydroxyprogesterone kits: the double antibody method, the coated tube method (ACTIVE), both from Diagnostic Systems Laboratories, Inc. (DSL) and the coated tube method (COAT-A-COUNT) from Diagnostic Products Corporation (DPC). The assay performance of the two DSL kits was very similar in terms of sensitivity, intra- and inter-assay precision, linearity of dilution, recovery, and specificity. We also analyzed 190 samples for 17 alpha-hydroxyprogesterone values using the above three kits. Twenty-three subjects were from prepubertal population (ages 1 month-13 years), thirty subjects were normal adult males (ages 20-53 years) and the remaining subjects were females in different phase of menstrual cycle (n = 40), on oral contraceptives (n = 20), post-menopausal (n = 17), or pregnant women in their first, second, or third trimester (n = 60). In addition to these 60 pregnancy samples, we analyzed serial samples from 3 pregnancies. 17 alpha-OHP levels paralleled the progesterone levels in all three kits. Although there was reasonable correlation between the DPC and the two DSL kits, the 17 alpha-OHP values were found to be significantly higher with DPC kit during the 2nd and 3rd trimester of pregnancy indicating probable interference in the DPC assay by some structurally related steroids present during pregnancy. The DSL assays may be particularly well suited for measuring 17 alpha-OHP levels during pregnancy.