Treatment of severe thyroid function disorders and changes in body composition

Hyper- and hypothyroidism are accompanied by altered metabolic rate, thermogenesis, and body weight. The aim of this study was to estimate the relation between treatment-induced changes in thyroid function, and the accompanying body composition in patients with either severe hypo- or hyperthyroidism.

Body composition analysis and hormonal assessment were measured at the initial diagnosis of thyroid disorder, after three-month treatment, and finally after complete recovery from hyperthyroidism (n = 18) or hypothyroidism (n = 27). Nonparametric Spearman correlation was used to analyse the relation between thyroid hormones and body composition as well as their respective changes.

In hypothyroid patients applied treatment significantly reduced (p < 0.05) total body weight, mainly due to a decrease in fat mass, whereas in hyperthyroid patients it caused a weight gain, with a simultaneous increase in muscle, water and fat mass. Total body weight and fat mass were significantly correlated with thyroid hormones' concentrations in all patients. Changes of fat, water, or muscle mass were strongly correlated with the changes in the patients' hormonal status.

Body composition is related to the concentration of thyroid hormones in thyroid dysfunction. Treatment-induced changes in thyroid hormones concentrations are correlated with the magnitude of the change of body weight, including muscle, water, and fat amount. (Endokrynol Pol 2016; 67 (4): 359-366).