[Studies on the measurements of LH-releasing hormone (LH-RH) by radioimmunoassay (RIA) (author's transl)].

The radioimmunoassay for LH-RH would aid greatly in the assessment of hypothalamic function. The anti-LH-RH was prepared by immunizing rabbits with LH-RH conjugate of BSA. 125I-LH-RH was prepared by the lactoperoxidase method and Sephadex G-10 column chromatography. The double antibody RIA technique was employed. On the assay of biological materials, LH-RH was extracted by methanol because LH-RH was rapidly destroyed in the serum, and this breakdown could not be prevented by benzamidine or 2,3-dimercaptopropranol. Sensitivity of this RIA system ranged from 10 tp 104 pg/ml, and the coefficient of variations of intra- and interassay were 12.9% and 9.% respectively. The serum LH-RH levels of men in a normal gonad state were below 10 pg/ml, and those of women in a normal gonad state in the early follicular or luteal phase were below 50 pg/ml. Whereas those of postmenopausal or castrated women were increased, and were highest in women with several gonadal disturbed states. The disappearance curve of LH-RH in women was characterized by two exponentials, t(1/2) of the initial component was 4.9 min, and that of the second component 24.6 min. Urinary excretion of exogenously administered LH-RH was also studied.