| Abstract: | Gonadotropin and steroid radioimmunoassays (RIAs) have been run in our laboratory for the past 6 years. Recently, the progesterone RIA was unpredictable when performed by one technician. After checking the mechanics and reagents, it was discovered that the technician had changed from Ortho Novum 1 + 50 to Ovral about the time the RIA became erratic. Standard curves of progesterone RIAs performed while the technician was taking either Ortho Novum 1 + 50 or Ovral, or on no contraceptive are reported. The data suggest that a probably exhaled metabolic product of norgestrel, the synthetic progestin in Ovral, interferes with the progesterone RIA and indicate an additional variable investigators must eliminate in performing RIAs. |
