Metabolic clearance of human follicle-stimulating hormone assessed by radioimmunoassay, immunoradiometric assay, and in vitro Sertoli cell bioassay.
We measured the equilibrium MCR of purified human FSH via continuous infusion and its half-life by bolus injection in gonadotropin-deficient men. Serum FSH concentrations were determined by RIA, immunoradiometric assay, and an in vitro FSH bioassay (rat Sertoli cell). At steady state, the MCR of FSH averaged 5.4 +/- 0.4 mL/min.m2, which was not statistically different in the three assays at the three different infusion rates. The half-life of FSH after bolus injection averaged 274 +/- 45 min (4.6 +/- 0.75 h) when analyzed as a single exponential, and 1.8 and 10 h for biexponential kinetics. The distribution volume of FSH was 3.1 L (immunoradiometric assay) and 2.1 L (bioassay). In summary, the MCR of human FSH is invariant across a range of physiological gonadotropin concentrations and quantitatively similar in three different immunological/biological assays. These results support the hypothesis that removal of circulating FSH molecules proceeds in parallel for immunoreactive and biologically active glycoprotein hormone.
Urban
R J
RJ
Department of Internal Medicine, NSF Science Center, University of Virginia Health Sciences Center, Charlottesville 22908.
Padmanabhan
V
V
Beitins
I
I
Veldhuis
J D
JD
D000328:Adult; D000818:Animals; D001681:Biological Assay; D002478:Cells, Cultured; D005640:Follicle Stimulating Hormone / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D006801:Humans; D015592:Immunoradiometric Assay; D066298:In Vitro Techniques; D007275:Injections, Intravenous; D008297:Male; D008657:Metabolic Clearance Rate; D011863:Radioimmunoassay; D051381:Rats; D012708:Sertoli Cells / Q000378:metabolism*
D005640:Follicle Stimulating Hormone