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.