[Studies on 17 alpha, 20 alpha-dihydroxy-4-pregnen-3-one in non-pregnant and pregnant women by a new radioimmunoassay system].

17 alpha, 20 alpha-dihydroxy-4-pregnen-3-one (17 alpha, 20 alpha-P) is reportedly a hyper-tensinogenic substance in a model of ACTH induced hypertension in sheep (Scoggins et al). This steroid has not previously been measured in Japan. We have developed a new radioimmunoassay (RIA) system for 17 alpha, 20 alpha-P, and measured this steroid in peripheral blood samples from non-pregnant and pregnant women. In this clinical investigation concentrations of 17 alpha-hydroxyprogesterone (17 alpha-OHP) and progesterone (P) were also measured in the same clinical samples. Specific anti-serum against 17 alpha, 20 alpha-P-3-carboxymethyloxime-BSA was generated in rabbits. Cross-reactions with 5-pregnen-3 beta, 17 alpha 20 alpha-triol (17 alpha, 20 alpha-P5) and 17 alpha-OHP were 42 and 2.4%, respectively. Other steroids showed cross-reactivity of less than 1%. As an internal standard dexamethasone (500 ng/100 microliter) was added to the samples which were extracted twice with 6 volumes of dichloromethane. Separation of the plasma extract was performed by high performance liquid chromatography (HPLC) with the ODS column in the solvent system, acetonitrile:water = 55:45. Eluates of the 17 alpha, 20 alpha-P and 17 alpha-OHP fractions were collected separately and the solvent was evaporated in vacuo. RIA was carried out on each extract with specific anti-sera. RIA of P was performed independently using the anti-P-3-CMO-BSA antiserum; 0.1 ml of serum was extracted with n-hexane and subjected to RIA without chromatography. The coefficient of variation for intra- and interassay (n = 10) were 8.5 and 11.7% for 17 alpha, 20 alpha-P; 7.2 and 12.1% for 17-OHP and 10.5 and 14.0% for P, respectively. The recovery rates of 17 alpha, 20 alpha-P, 17 alpha-OHP and P were 95 +/- 1.5, 93.2 +/- 3.5 and 97.5 +/- 4.2%, respectively. With the use of this method, 17 alpha, 20 alpha-P was measured in the blood samples from the menstrual cycle and normal pregnancy. The mean serum 17 alpha, 20 alpha-P concentrations +/- SD in the follicular, ovulatory and luteal phases, and in the first, second and third trimesters were; 76 +/- 6.0, 100 +/- 31, 101 +/- 6.4, 226 +/- 80, 151 +/- 48 and 367 +/- 99 pg/ml, respectively.(ABSTRACT TRUNCATED AT 400 WORDS)