Prevalence of elevated thyroid-stimulating hormone levels in obese children and adolescents

To determine the prevalence of elevated thyroid-stimulating hormone (TSH) levels in obese children and adolescents referred to pediatric endocrinology clinics.

We undertook a retrospective review of medical records of 191 obese and 125 nonobese children (younger than 18 years old). Data about age, sex, body mass index, TSH, thyroid functions, thyroid antibodies, thyroid size, and medications were collected.

Six obese patients had Hashimoto disease and TSH values from 0.73 to 12.73 mIU/L; they were excluded from the study analyses. Of the remaining 185 obese subjects, 20 (10.8%) had TSH levels >4 mIU/L, but no control subject measurement exceeded this TSH value. The highest TSH concentration in an obese study subject was 7.51 mIU/L. When obese children with TSH levels >4 mIU/L were classified in a third group, the mean TSH in the rest of the obese children was comparable with that in the control group (1.98 +/- 0.84 [SD] and 1.95 +/- 0.80 mIU/L, respectively; post hoc analysis of variance, P = .945). Obese subjects with increased TSH values had a mean body mass index similar to that for obese subjects with normal TSH levels (34.98 +/- 6.12 [SD] and 34.29 +/- 7.84 kg/m2, respectively).

Mild elevation of TSH values in the absence of autoimmune thyroid disease is not uncommon in some obese children and adolescents. This is the second study in the United States to report this observation. Our study did not identify any special characteristics of obese subjects with TSH elevation in comparison with obese children with normal TSH levels and the control group. Current medical knowledge does not support routine screening for thyroid dysfunction in obese children.