LEXINGTON, Ky., Jan. 4 -- Correcting the hormonal deficit caused by hypothyroidism did not trigger significant weight loss in children with acquired hypothyroidism.
After 4.4 months of treatment of children with levothyroxine, mean thyroid-stimulating hormone (TSH) concentrations decreased from 147 mU/mL to 5.0 147 mU/mL, but only those children with the highest baseline TSH concentrations lost weight, Jefferson P. Lomenick, M.D., of the University of Kentucky here, and colleagues reported in the January issue of the Journal of Pediatrics.
Action Points
- Explain to interested patients that this study confirms earlier studies in adults that have found little impact on weight with successful treatment of hypothyroidism.
- Point out that the implication of this study is that hypothyroidism is not a cause of obesity.
The association between weight gain and hypothyroidism is well recognized by both physicians and patients, they noted. Yet, this study confirmed that evidence did not "support the notion of hypothyroidism as a cause of obesity," they added.
Dr. Lomenick advised physicians to be cautious in their own expectations of a weight loss benefit with treatment, and to explain the likely impact of treatment to parents and children.
Dr. Lomenick and colleagues retrospectively identified 68 children who were treated for acquired hypothyroidism from 1995 through 2006.
The mean age of all children was 10.8 years, and those with severe hypothyroidism (mean TSH, 349 mU/ml) were 11.0. Seventy-one percent of that group was overweight or obese at baseline, versus 51% of those with lower TSH concentrations.
Sixty-seven of the children were thought to have Hashimoto's thyroiditis, while one child had hypothyroidism secondary to lithium therapy. Most of the children (81%) were girls.
Overall, normalization of TSH was not associated with a significant change in mean weight (51.0 to 52.1 kg, P =0.79), nor was there a significant difference in mean weight percentile. Likewise, there were no significant changes in BMI.
The only children with measurable weight loss were those who had a mean baseline TSH of 349 mU/mL. They had a mean weight loss of 2.3 kg (range, 0.6 to 7.3 kg), but this, too, was not significant (P=0.81). Moreover, the authors cautioned that "much of this weight loss may have been myxedema."
Dr. Lomenick said the findings mirror studies in adults that have found treatment "producing mild short-term weight loss with minimal long-term change."
The study had a number of limitations beyond its retrospective design, including the variable nature of TSH measurements, lack of standardized measurement techniques for height and weight, and lack of a standardized weight-counseling program.
| The study received no industry support and Dr. Lomenick disclosed no competing financial interests. |
Primary Source
The Journal of Pediatrics
Lomenick JP, J Pediatr 2008; 152: 96-100.