ESPE Abstracts

Objectives: Obesity is a well-known risk factor for central precocious puberty (CPP). Recently, elevated thyroid stimulating hormone (TSH) were reported in obese youth. However, few data regarding the relationship between CPP and TSH are available. The aim of this study was to evaluate thyroid function in CPP girls and the relationship between CPP and serum TSH concentration.

Methods: This is a retrospective cross-sectional study. A total 1,247 girls aged 6–8 years who underwent gonadotropin-releasing hormone (GnRH) stimulation test were included. Medical records of all subjects were reviewed. Subjects were classified into CPP (n=554) and control (n=693) groups according to the results of GnRH stimulation test. Subclinical hypothyroidism was defined as elevated TSH with normal free T4 (TSH ≥5.0 mIU/L and free T4 ≥0.8 ng/dl). Characteristic and laboratory data between CPP and control groups were compared. Correlations of characteristic and laboratory data with TSH concentration were evaluated.

Results: There were no significant differences in age, height, height standard deviation score (SDS), insulin-like growth factor binding protein (IGFBP)-3 and IGFBP-3 SDS between CPP and control groups. Bone age, bone age advance, alkaline phosphatase, insulin-like growth factor (IGF)-I, IGF-I SDS, basal and peak luteinizing hormone (LH) and basal and peak follicular stimulating hormone (FSH) were significantly higher in CPP than in control group. Weight SDS and BMI SDS were significantly higher in control than CPP group. Serum TSH concentration of CPP group was significantly higher than that of control group (3.19±1.55 vs. 2.58±1.34 mIU/l, P<0.001). Serum free T4 concentration of CPP group was significantly lower than that of control group (1.38±0.14 vs. 1.44±0.18 ng/dL, P<0.001). Among all subjects, 149 girls (11.9%) had subclinical hypothyroidism. The prevalence of subclinical hypothyroidism was higher in CPP group compared to control group (15.7 vs. 8.9%, P<0.001). TSH concentrations were positively correlated with age, height, weight, BMI, bone age, alkaline phosphatase, IGF-I, IGF-I SDS, basal LH, peak LH and basal FSH. Multiple linear regression analysis showed that age (β=0.574, P<0.001) and peak LH (β=0.016, P=0.021) were independent predictors of serum TSH concentration.

Conclusion: Subclinical hypothyroidism in CPP girls should be associated with pubertal LH elevation.