A new approach in the evaluation of gonadotropins for the diagnosis of polycystic ovary syndrome.

The new immunometric methods using monoclonal antibodies to detect gonadotropins revealed a reduction in the absolute values of these hormones, especially LH, due to a decrease in cross-reaction between gonadotropin subunits. Therefore, reference values of the LH/FSH ratio and their diagnostic significance in the polycystic ovary syndrome (PCOS) need to be defined again. We evaluated the LH/-FSH ratio in basal conditions and after administration of GnRH (100 micrograms as i.v. bolus) in seventy patients with PCOS employing an immunoenzymatic method. In PCOS patients the LH/FSH ratio was greater than 1 in 70% when evaluated on a single sample and in 88% when evaluated on a pooled serum from four samples every 30 minutes; in the control group the ratio was always lower than 1. The LH/-FSH ratio evaluated on the peak values in response to GnRH was greater than 2 in all patients and lower than 2 in the control group. Our results indicate that the LH/FSH ratio is still an important diagnostic tool in PCOS, especially when evaluated on the peak values in response to GnRH, even if its reference values are lower using these new monoclonal methods.