Comparative study of serum luteinizing hormone levels in human subjects as measured by radioimmunoassay and radioreceptorassay.

A rapid, precise, sensitive, and specific radioreceptorassay (RRA) for serum luteinizing hormone (LH), using a 15,000 X g pellet from bovine corpora lutea, was developed. A comparative study of the serum LH levels in human subjects as measured by this RRA and by radioimmunoassay (RIA) using the same standard preparation was then conducted. The serum LH profile throughout the entire menstrual cycle and the pituitary responsiveness to LH-releasing hormone (LH-RH) stimulation during the two phases of the cycle were studied in two normal women. In addition, LH levels in two normal postpubertal men were measured in blood samples obtained before and after LH-RH administration. Similar, although not identical, LH profiles were found in all cases by both hormone assay methods. Higher RRA-assayable LH values were obtained throughout the menstrual cycle as compared with those obtained by RIA. A significant LH-RH pituitary response in terms of LH in both RRA and RIA during the luteal phase was observed as compared with that observed during the early follicular phase. In the two normal men, the LH values obtained with RRA were higher than those obtained with RIA. It is concluded that the LH RRA is a practical and efficient tool for clinical research.