Monoclonal-antibody-based noncompetitive avidin-biotin assay for lutropin in urine.

This noncompetitive avidin-biotin assay for lutropin (LH) in urine is based on the use of solid-phase, monoclonal antibodies, avidin-biotin binding, and enzyme label. The detection limit for LH is 0.5 int. unit/L. Performance time is 2 h. Intra- and interassay CVs were 4.2% and 6.2%, respectively. The assay is more specific for intact LH than are RIAs, and the results are unambiguous as compared with those by RIAs. LH is stable for a week in refrigerated urine; thus urine is a convenient sample material in follow-up studies for clinical ovulation timing. This rapid and sensitive nonisotopic LH assay avoids the disadvantages of blood samples. The assay provides clinically relevant predictions of ovulation timing from the amount of hormone measured in a 3-h urine specimen.