ESPE Abstracts

Background: Prior research has shown a correlation between TSH levels and BMI in euthyroid subjects. Whether this relation can be applied to hypothyroid chemically euthyroid children has yet to be determined.

Objective and hypotheses: To determine if there is a correlation between TSH levels and BMI percentiles in hypothyroid children who are chemically euthyroid on levothyroxine.

Method: Retrospective chart review of patients from Rush University Medical Center and Stroger Hospital (Chicago, IL, USA) from 2008 to 2014. 154 children aged (6 months and 21 years) with a diagnosis of primary hypothyroidism that were on levothyroxine therapy for at least 6 months and chemically euthyroid were included. Normal TSH levels were divided into three groups: T1 (0.34–1.5 mIU/l), T2 (1.6–2.5 mIU/l), and T3 (2.6–5.6 mIU/l). Data was analysed by cross tabulation (χ²).

Results: A total 154 patients (mean age±S.D.: 12.69±6.84 years, median age=14.88, 68% females and 32% males) were evaluated. These included 24.7% obese children (BMI percentile >95%), 20.7% overweight (BMI >85–95%), and 54.5% healthy weight (BMI <85%). There was a significant positive correlation between TSH and BMI percentiles (r=0.283, P value <0.001). The percentage of hypothyroid children who were chemically euthyroid with healthy BMI percentiles in TSH group T1 was 40.5%, while 29.8% in both TSH group T2 and TSH group T3 respectively. The percentage of hypothyroid children with obesity was 18.1% in TSH group T1 and 60.5% in TSH group T3. Pearson’s χ² P value=0.013.

Conclusion: In hypothyroid children who are chemically euthyroid, there is a positive correlation between higher TSH levels (within the normal range) and elevated BMI percentiles. Our results indicate that keeping the TSH levels into the lower third (0.34–1.5 mIU/l) of the normal range may result in a healthier BMI.