Obesity exhibits subclinical hypothyroidism (SH) and acanthosis nigricans (AN) easily as an associated complication. We aimed to elucidate the triad interlink between the thyroid hormone levels, fat distribution and AN. In this cross-sectional study, 202 obese men and 239 obese women were enrolled. Anthropometric measurements, glucose-lipid metabolism, thyroid hormone levels, and fat distribution were measured. SH was defined by thyroid-stimulating hormone (TSH) less than 2.5 mU/L. Results showed that the prevalence of AN was significantly higher in the obese group with SH than without SH (47.3% vs. 36.9%, P=0.035). The number of obese women with SH was larger than men (38.1% vs. 28.2%, P=0.029). Obese women have higher TSH levels, lower free triiodothyronine (FT3) and free thyroxin (FT4) than obese men (all P<0.01). In all obesity, FT3 was significantly positively associated with weight, NC, WC, WHR, SBP, DBP, FINS, UA and negatively with HDL-C (all P <0.05). FT4 was significantly positively associated with weight, BMI, NC, WC, SBP, DBP, UA, HGB and FBG (all P <0.05). TSH was negatively correlated with FBG and HGB (all P <0.05). FT3 was positively correlated with Peripheral fat mass, total lean mass and negatively with Total Fat% and Trunk/peripheral fat mass (P=0.025;P=0.029;P<0.001;P=0.034), FT4 was also positively with total lean mass and negatively with Total Fat%(P=0.008; P=0.017), and TSH was positively correlated with Total Fat%(P=0.032).
In conclusion, we found that obese patients with SH are more susceptible to AN. Relatively insufficient thyroid function with higher TSH may be a protective factor in obese women with a better metabolism. Thyroid hormone may be beneficial in improving fat distribution and building lean mass in patients with obesity.
S. Qu: None. X. Wang: None.
National Key Research and Development Program of China (2018YFC1314100); National Natural Science Foundation of China (81970677)