Experience with a radioimmunoassay of luteinizing hormone-releasing hormone (LH-RH) in biological material of man.

A radioimmunoassay of LH-RH with a sensitivity of 7.8 pg/ml is described. Labelling and purification techniques, methods for extraction of LH-RH and separation techniques of bound and free labelled hormone are compared. Determination of LH-RH levels in serum after administration of synthetic LH-RH by different routes and measurements of endogenous LH-RH levels in serum of normal subjects and patients with different endocrine diseases as well as in cerebrospinal fluid of normal men are performed. The measurement of exogenously administered LH-RH in serum reflects the disappearance of synthetic LH-RH from peripheral circulation in dependence upon the kind of administration route. The level of endogenous LH-RH was found to be under the limit of the assay in all samples of cerebrospinal fluid and of serum of normal male subjects. The results obtained in the patient groups show that the radioimmunological estimation of endogenous LH-RH in peripheral body fluids does not reflect the hypophysiotrophic role of this hypothalamic peptide.