Short-term Change in Resting Energy Expenditure and Body Compositions in Therapeutic Process for Graves' Disease

Abstract

Objective In the medical treatment of Graves' disease, we sometimes encounter patients who gain weight after the onset of the disease. To estimate the energy required during the course of treatment when hyperthyroidism ameliorates, we measured the resting energy expenditure (REE) and body composition in patients with Graves' disease before and during treatment in the short-term. Methods Twenty patients with newly diagnosed Graves' disease were enrolled, and our REE data of 19 healthy volunteers were used. The REE was measured by a metabolic analyzer, and the basal energy expenditure (BEE) was estimated by the Harris-Benedict formula. The body composition, including body weight, fat mass (FM), muscle mass (MM) and lean body mass (LBM), were measured by a multi-frequency body composition analyzer. We tailored the nutritional guidance based on the measured REE. Results Serum thyrotropin levels were significantly increased at three and six months. Serum free thyroxine, free triiodothyronine and REE values were significantly decreased at one, three and six months. The REE/BEE ratio was 1.58±0.28 at the onset and significantly declined to 1.34±0.34, 1.06±0.19 and 1.01±0.16 at 1, 3 and 6 months, respectively. Body weight, MM and LBM significantly increased at three and six months. Conclusion The REE significantly decreased during treatment of Graves' disease. The decline was evident as early as one month after treatment. The REE after treatment was lower than in healthy volunteers, which may lead to weight gain. These data suggest that appropriate nutritional guidance is necessary with short-term treatment before the body weight normalizes in order to prevent an overweight condition and the emergence of metabolic disorders.

Keywords: Graves' disease; hyperthyroidism; resting energy expenditure; resting metabolic rate.

Figure 1.

Correlations between the indicators of energy expenditure [REE (A-C) and the REE/BEE ratio (D-F)] and the thyroid function [TSH (A and D), free T3 (B and E) and free T4 (C and F)] are plotted. A linear regression model was used for the analysis. REE: resting energy expenditure, BEE: basal energy expenditure, TSH: thyrotropin, T3: triiodothyronine, T4: thyroxine

Figure 2.

Changes in the thyroid function, the TSH (A), free T3 (B) and free T4 (C), and the indicators of energy expenditure, the REE (D) and REE/BEE ratio (E), during treatment are plotted. Data are shown as the mean±SD. *, p<0.01; **, p<0.005; †, p<0.001; ††, p<0.0005. P values were corrected according to Wilcoxon’s signed-rank test vs. the onset. #, p<0.05; ##, p<0.01; ###, p<0.0001. P values were corrected according to the Mann-Whitney U test vs. healthy controls. TSH: thyrotropin, T3: triiodothyronine, T4: thyroxine, REE: resting energy expenditure, BEE: basal energy expenditure