Treatment of paediatric hyperthyroidism but not hypothyroidism has a significant effect on weight

Abstract

Objective-Thyroid hormones are involved in metabolic regulation, but the degree to which they affect body weight and body mass index (BMI) in children is unclear. We examined the effect of hypo-and hyperthyroidism on weight and BMI at the time of diagnosis and after appropriate treatment. Design-Prospective and retrospective case seriesPatients-Children referred for thyroid dysfunction were enrolled prospectively if their total or free T4 was elevated with TSH <0.05 mIU/mL (N=57) or if they had a subnormal total or free T4 and TSH >20 (N=29).Results-Almost all patients had at least 2 classic signs or symptoms including goiter, but hyperthyroid patients had more symptoms. Mean BMI z scores at the time of diagnosis did not significantly differ between the two groups. Males with hyperthyroidism complained of weight loss more frequently and had a lower pretreatment BMI z score than hyperthyroid females. Hypothyroid patients lost a minimal amount of weight by the first follow-up (mean of 0.3 kilograms (kg)) and on average gained weight by the second follow-up visit. In contrast hyperthyroid patients gained a mean of 3.4 kg at the first follow-up visit and a mean of 7.1 kg by the second.Conclusions-Correction of hypothyroidism resulted in minimal weight loss, suggesting that hypothyroidism does not cause significant weight gain in children. In contrast, correction of the hyperthyroid state had a somewhat greater impact on weight status. These results are consistent with prior reports but surprising given the opposite metabolic effects of hypo-and hyperthyroidism.

Thyroid hormone and obesity

“…Eightyseven hyperthyroid patients had lost a mean of 16% of their body weights before hyperthyroidism at the time of presentation; 2 years following initiation of treatment, they had regained and slightly exceeded their baseline weight. A recent study of weight change following treatment of thyroid dysfunction in 57 hyperthyroid and 29 hypothyroid children similarly found that weight loss was minimal following treatment for hypothyroidism (mean 0.3 kg by the first follow-up visit) [5]. However, there was an average 7.1 kg gain in weight by the second follow-up visit following initiation of treatment for hyperthyroidism.…”

Weight gain after treatment of Graves’ disease in children

“…Information about weight gain during treatment of hyperthyroidism in children and adolescents is limited, and no studies identify predictors of weight gain in this population. In one study, patients predominantly receiving medical therapy had significant body mass index Z score (BMI‐Z) increases evident by 3 months after presentation that persisted throughout a 36‐month follow‐up period …”

Associations between adiposity and indicators of thyroid status in children and adolescents

“…Low thyroid hormone is associated with reduced energy expenditures (6) and fluid retention (7) in adults with overt hypothyroidism. However, less severe hypothyroidism does not appear to induce greater body fatness or weight, since l-thyroxine replacement leads to relatively small changes in body composition (8, 9). Elevated thyroid stimulating hormone (TSH) that does not exceed 2.5 times the upper limit of the normal range in association with a normal free thyroxine (FT4) concentration, referred to as “subclinical hypothyroidism,” is frequently observed in adults with obesity who have no evidence of autoimmune thyroiditis (10).…”