Endocrine Abstracts

Introduction: Both TSH and prolactin serum levels within normal range were previously reported to be associated with metabolic parameters.

Aim: To analyse the connections between serum levels of prolactin, TSH, and insulin resistance in polycystic ovary syndrome patients.

Material and methods: 322 PCOS patients (mean age 24.3±5.16 years and mean BMI 28±7.57 kg/m²) with normal serum prolactin and without thyroid dysfunction evaluated between January 2007 and January 2014 were included in the study. Anthropometric, metabolic, and hormonal parameters were measured in all the patients. HOMA-IR was calculated as an index of insulin resistance.

Results: HOMA-IR was negatively correlated with serum prolactin (P=0.001) and positively with serum TSH (P=0.03) and with adiposity indices (BMI P<0.0001, waist P<0.0001, and waist:hip ratio P<0.0001). In multivariate linear regression both prolactin (β=−0.203, P=0.015) and TSH (β=0.165, P<0.05) were independently associated with HOMA-IR. Several models of multivariate linear regression were built with HOMA-IR as dependent variable and all the parameters associated with HOMA-IR in bivariate analysis as independent variables. In each model one of the adiposity indices (BMI, waist, or waist:hip ratios) were included in order to avoid collinearity. In these models the only independent predictor for HOMA-IR was adiposity.

Conclusion: Although, both TSH and prolactin serum levels were related to insulin resistance, this connection seems to be due to the interplay between adiposity and all these parameters in PCOS patients.