Association of subclinical hypothyroidism and phenotype, insulin resistance, and lipid parameters in young women with polycystic ovary syndrome

Objective: To determine whether subclinical hypothyroidism (SCH) alters the phenotype, insulin resistance, or lipid parameters in young women with polycystic ovary syndrome (PCOS). Design: Prospective case-control study. Setting: Tertiary care setting. Patient(s): Sixty-two young women with PCOS and SCH (group I) and 291 euthyroid women with PCOS (group II). Intervention(s): Recording of clinical, biochemical, hormonal profile, and parameters of insulin resistance. Main Outcome Measure(s): Whether SCH has any association with clinical parameters like hirsutism, menstrual disturbances, lipid profile, and parameters of insulin sensitivity. Result(s): Mean (+/- SD) TSH was 7.13 +/- 1.28 IU/L in group I and 2.51 +/- 1.21 IU/ L in group II, with comparable free triiodothyronine and free thyroxine. The two groups were comparable in age, weight, and body mass index. Parameters like blood pressure, menstrual pattern, and degree and duration of hirsutism did not differ between the two groups. Serum concentrations of triglycerides were significantly higher in the SCH group compared with controls. Plasma glucose concentrations both in fasting and after oral glucose tolerance test were similar between the two groups. Fasting insulin and other parameters of insulin resistance were not altered by SCH. Conclusion(s): Mild TSH elevation in the face of normal serum free triiodothyronine and free thyroxine results in a mild increase in serum lipids. Subclinical hypothyroidism is not associated with alteration in phenotypic expression and insulin resistance in young women with PCOS. (Fertil Steril (R) 2011; 95:2039-43. (C) 2011 by American Society for Reproductive Medicine.)