A one-hour radio-immuno-assay for lutropin

For the rapid estimation of the mid-cycle lutropin peak, a commercially available four-hour lutropin radioimmunoassay kit was modified by shortening the incubation time, raising the incubation temperature and using more concentrated antisera. This RIA then required 60 min for completion. The results were compared to a commonly used 24-hour RIA from another commercial source. Calibration curves and lutropin profiles of the patients did not differ significantly. The shortened RIA is particularly suitable for a rapid and reliable estimation of the lutropin peak/ovulation time.