Critical analysis of methods for estimating production rates of FSH

The urinary excretion method and the constant infusion technique were used to estimate hFSH production rates (PR) in three normal men (aged 25-40 years). Both studies were also done in a hypophysectomized nine year old boy. The PR of hFSH in the urinary excretion studies ranged from 20.0 to 45.7 IU/24 h, whereas the constant infusion studies yielded PR's of 68.7 to 107.8 IU/24 h. Possible reasons for the discrepancy of the results obtained by the two methods are discussed. In the hypophysectomized patient, the metabolic clearance rate (MCR) of infused hFSH was much lower (4.3 ml/min) than in the normal adults (7.8 to 12.0 ml/min) and was not affected by the dose of hFSH given.