Luteinizing Hormone Activity of Human Pituitary Gonadotropin as Determined by the Ventral Prostate Weight and the Ovarian Ascorbic Acid Depletion Methods of Assay

Abstract

The luteinizing hormone (LH) activity of 3 preparations of human pituitary gonadotropin (HPG) made from post-menopausal urine, of 1 HPG preparations made from male urine and of 1 HPG preparations made from the urine of eunuchs was determined by 2 assay systems: the ovarian ascorbic acid depletion (OAAD) method and the ventral prostate weight (VPW) method with ovine NIH-LH-S1 as standard. It was found that the VPW method indicated the presence of 12 times more LH activity in the 5 HPG preparations than did the OAAD method. In the search for an explanation for this discrepancy, the OAAD and the VPW methods for assay of LH activity were analyzed with respect to sensitivity, accuracy and interference by other hormones. Consideration also was given to the relationship of the 2 bio-assay systems to the chemical and physical nature of the preparations and to the effect of over-all rate of metabolism of the hormone. It was concluded that: 1) the discrepancy in LH estimation by the 2 assay systems employed was probably due to differences in the chemical and physical nature of LH in the ovine LH standard and in the HPG; 2) comparison of LH activity contained in HPG extracts by means of the OAAD and VPW methods should be conducted in terms of a suitable HPG standard and not in terms of the ovine NIH-LH standards; and 3) the OAAD method is 9 times more sensitive than the VPW method to LH prepared from sheep pituitary glands but is not more sensitive to LH in urine of men, postmenopausal women or eunuchs.