Standardization of therapeutic, urinary gonadotrophins: An update on the use and availability of International Standards for Menotrophin

• Preparations of human, urinary-derived FSH and LH are used to treat infertility.
• WHO International Standards (IS) define the Units (IU) of FSH and LH bioactivities.
• The 5th IS for urinary FSH and LH for bioassay was calibrated in a collaborative study.
• The 5th IS contains 183 IU per ampoule FSH bioactivity and 177 IU per ampoule LH bioactivity.
• We summarize the origins of WHO IS for assignment of FSH and LH bioactivities.

The potencies of therapeutic preparations of gonadotrophins of human, urinary origin, which comprise a heterogenous mix of isoforms with follicle-stimulating hormone (FSH) and luteinizing hormone (LH) bioactivities, are standardized by WHO International Standards (IS). We report here, the evaluation, through an international collaborative study, of a candidate preparation, coded 10/286, to replace the 4th IS, 98/704, for human, urinary FSH and LH (Menotrophin) which has been used for many years for the potency assignment of therapeutic preparations using bioassays. The mean FSH and LH bioactivities of 10/286, determined by in vivo bioassays in terms of 98/704, were 183 IU per ampoule (95% confidence limits 165–202) and 177 IU per ampoule (95% confidence limits 159–197), respectively.