A correlation analysis of subclinical hypothyroidism with body composition and insulin resistance in overweight/obese patients with polycystic ovary syndrome

Abstract

Objective To determine the association of subclinical hypothyroidism (SCH) with body composition (measured by body impedance analysis) and insulin resistance (IR) in overweight/obese patients with polycystic ovary syndrome (PCOS). Methods A retrospective analysis was conducted of the clinical records of 109 overweight or obese [body mass index(BMI)≥24 kg/m2] PCOS patients who visited the Department of Endocrinology and Fertility Center of Nanjing Drum Tower Hospital between April 2013 and April 2016 for menstrual disorder or infertility and were referred to receive weight management. 24 of the patients had SCH, and 85 had euthyroid (EU). We determined the body composition of the patients with Biospace Inbody 720 body composition analyzer, measured the patients' serum lipid profiles, conducted in each patient the 75 g oral glucose tolerance test and the insulin release test, and calculated the homeostasis model assessment of insulin resistance (HOMA-IR) indices. Results Patients with SCH and autoimmune thyroiditis (AIT) accounted for 22.02% and 24.36% of the total. The obesity level[(145.19±13.75)% vs.(153.31±18.15)%, t=-2.032, P=0.045], VFA[(132.48±20.85)cm2vs.(147.35±24.26 )cm2, t=-2.730, P=0.007], body fat (BF) [(31.91±5.88)kg vs.(35.43±6.89) kg, t=-2.274, P=0.025], body fat percentage (BFP) [(40.92±3.701)% vs.(43.07±4.26)%, t=-2.241, P=0.027], body mass index (BMI)[(30.49±2.88)kg/m2vs.(32.19±3.81)kg/m2,t=-2.026, P=0.045]and waist circumference (WC) [(98.34±7.13)cm vs.(102.86±8.74)cm, t=-2.324, P=0.022]of SCH group were significantly lower than those of euthyroid , with significant statistical difference. The levels of serum thyroid hormone (TSH) in patients with EU were positively correlated with the degree of obesity, the BF, the BFP, the BMI and the hip circumference (P=0.019, 0.042, 0.025, 0.019, 0.039), but not with the VFA (t=1.797, P=0.076). There were no statistically significant differences (P> 0.05) between patients with SCH and those with EU in their HOMA-IR indices, insulin levels, blood glucose, blood lipid, and ratio of IR (defined as HOMA-IR≥2.69). Conclusions Obesity related body composition parameters were lower in PCOS patients with SCH than in those with EU. However, there was no significant difference between the two groups in blood lipid level and the ratio of IR. TSH levels in the EU group were correlated with the BMI and the BFP, but not with the VFA. A larger sample is needed to identify how and why thyroid hormones may affect the body composition and glycolipid metabolism of females with PCOS. Key words: Overweight and obesity; Polycystic ovary syndrome; Subclinical hypothyroidism; Body composition; Insulin resistance