부산대학교 도서관

STUDY QUESTION: Is thyroid function, as reflected by thyroid-stimulating hormone (TSH) levels, correlated with the gluco-insulinemic assessment and implicated in the clinical and hormonal abnormalities of women with polycystic ovary syndrome (PCOS)? SUMMARY ANSWER: In PCOS women, TSH levels are significantly correlated with the peripheral insulin-resistance (IR) and the pattern of body fat distribution, independently of age. In overweight/obese subjects, thyroid function is related also with insulin secretion. No correlations were found with body mass index (BMI), menstrual abnormalities, hirsutism score and hormonal assessment. WHAT IS KNOWN ALREADY: Hypothyroidism is frequently characterized by insulin resistance, which is also a hallmark of PCOS. Although subclinical hypotiroidism was found to be more prevalent in PCOS women than in the general population, a clear relationship between insulin resistance and thyroid dysfunction has not been established in these patients.Thyroid function is known to affect gonadal function, SHBG secretion and fertility. Few studies previously analyzed this aspect in the context of PCOS. STUDY DESIGN, SIZE, DURATION: This is a cohort study conducted from January to December 2012 at the Department of Obstetrics and Gynecology of the Università Cattolica Sacro Cuore, Rome. We studied 112 consecutive women affected by PCOS, attending our divisional outpatient services; 44 were overweight or obese (BMI >27 kg/m2) and 68 normal weight. PARTICIPANTS/MATERIALS, SETTING, METHODS: Inclusion criteria: PCOS women (age range 18-35 years), diagnosed according to Rotterdam criteria. Exclusion criteria: pregnancy, other endocrine dysfunctions, manifest hypothyroidism or hyperthyroidism, previous thyroid surgery or use of thyroid medications, hormonal drugs intake. Anthropometric parameters, hormonal assays, oral glucose tolerance test and euglycaemic-hyperinsulinaemic clamp were evaluated in all patients. MAIN RESULTS AND THE ROLE OF CHANCE: TSH values were above the normal range in 14.3% of participants. TSH was directly correlated with waist to hip ratio (r: 0.22; p = 0.03) and inversely correlated with M-clamp, a reliable measure of peripheral total body glucose utilization (r: -0.24; p = 0.03). Neither basal nor after-load glycemia were correlated with TSH.No correlations were found between TSH levels and gonadotrophins, plasma androgens (testosterone, androstenedione, DHEAS, 17OH progesterone), AMH, sex hormone-binding-globuline. Similarly, the hirsutism score and the menstrual pattern seemed not to be influenced by thyroid function.After dividing patients on the basis of BMI, TSH levels resulted positively correlated with both stimulated insulin secretion (r: 0.40; p = 0.009) and peripheral insulin resistance (r: 0.35; p = 0.04) in overweight-obese women, but not in the subgroup of normal weight PCOS women. LIMITATIONS, REASON FOR CAUTION: Lack of a non-PCOS control group. WIDER IMPLICATIONS OF THE FINDINGS: This study, for the first time in PCOS subjects, objectively analysed the relationship between thyroid and IR, assessed by the gold standard method euglycemic-hyperinsulinemic clamp. As a result, thyroid function seems to be linked to insulin metabolism in this syndrome. It remains to be determined if the relative TSH elevation may be a cause, presumably via systemic oxidative stress, or a consequence of IR, as suggested by previous reports on TSH normalization after insulin-sensitizers administration. STUDY FUNDING/COMPETING INTEREST(S): The authors have no interests to disclose. This study was not financed. TRIAL REGISTRATION NUMBER: It is an observational study.