[Measurement of biological activity of hLH. Multicenter study]

This report describes the results of a multicentric study of biological methods for luteinizing hormone (hLH). The production of testosterone by animal Leydig cells is used by five laboratories with different methodologies including rat, mouse and pig cells. Dose-response curves of testosterone production, quality criteria and results on a physiological population of men and women, are reported and discussed. It is concluded that the bioactive determination of hLH must be considered as a reference method used in discordances between clinic and immunological methods.