Bioassay of hormones.

Bioassay of hormones has a small but important role in defining the physiologic status of selected patients in whom immunoassay results do not correlate with clinical signs and symptoms. This article reviews three sensitive bioassays for hormones, which are based on 1) stimulation of adenylate cyclase in membrane preparations, 2) cytochemical changes in fresh tissue segments or sections, and 3) stimulation of cell replication in the Nb2 lymphoma cell culture. The adenylate cyclase assay using kidney membranes can measure parathyroid hormone (PTH), whereas assays using thyroid membranes can measure both thyrotropin (TSH) and thyroid-stimulating immunoglobulins (TSI). The cytochemical assay methods can measure numerous hormones, but the two most promising assays for clinical use are the PTH assay using guinea pig distal convoluted renal tubules and TSH/TSI assay using thyroid follicles. The Nb2 lactogenic assay is sensitive to biologic concentrations of growth hormone, prolactin, and human placental lactogen.