Changes in luteinizing hormone and insulin secretion in polycystic ovariansyndrome

Uncertainties regarding the pathogenetic changes underlying the polycystic ovarian syndrome (PCOS) have been reported. The aim of this study was to in vestigate the endocrine and metabolic features of PCOS patients in relation to luteinizing hormone (LH) secretion. Androgen assays, oral glucose toler ance tests, hyperinsulinaemic euglycaemic clamps and gonadotrophin releasin g hormone (GnRH) tests were performed in 100 patients. Sixty-six patients s cheduled as hyperinsulinaemic and 34 as normoinsulinaemic showed similar co ncentrations of LH, follicle stimulating hormone (FSH), LH/FSH ratio, and L H response to GnRH testing. Hyperinsulinaemic subjects showed higher body m ass index (BMI), insulin resistance, testosterone and free androgen index l evels compared with those of normoinsulinaemic subjects; when clustered in relation to their LH basal concentrations, the two groups obtained differed only in androstenedione concentrations, Considering both insulin and LH pl asma concentrations, four groups were obtained. Hyperinsulinaemia and hyper -LH secretion were not related in 54% and coexisted in the same subjects in 26% of cases. Hyperinsulinaemia as well as hyper-LH secretion affected the expression of the syndrome; the insulinaemia was directly correlated with testosterone concentrations and all metabolic parameters that affected the free androgen index. The LH concentrations were related to androgen product ion and were independent of BMI and insulin concentrations, It is concluded that the degree of hormonal alteration is the final sum of such pathogenet ic factors.