Weight Gain after Treatment of Hyperthyroidism is Associated with Impairment of Quality of Life

<b><i>Background:</i></b> There is evidence of quality of life (QoL) impairment and weight gain in treated hyperthyroidism. It is not known whether treatment-related weight gain is associated with QoL impairment in this patient group of this cohort. Our primary aim was to examine whether percentage weight gain (PWG) after treatment of hyperthyroidism was associated with QoL impairment. <b><i>Methods:</i></b> We enrolled patients with treated hyperthyroidism 6 months to 8 years after diagnosis. We obtained anthropometric measurements from a prospectively completed database. With a cross-sectional study design, we assessed QoL using the thyroid-specific patient-reported outcome (ThyPRO) tool. We pre-specified three dependent variables in ThyPRO: "cosmetic complaints," a composite of "tiredness and overall QoL" and "depressivity and anxiety" domains. We included age, sex, thyrotropin categories, comorbidities, and disease duration as covariates. We applied a generalized linear model (GLM) for the analysis. <b><i>Results:</i></b> We included 108 patients, including 68 (63%) females, with a mean (standard deviation [SD]) age 50 (14.5) years. The median weight at diagnosis was 65.5 (interquartile range [IQR]: 58.7, 75.5) kg and BMI was 23.9 (21.9, 27.1) kg/m², and at final evaluation, weight was 72.7 (64.1, 83.8) kg (<i>p</i> < 0.001) and BMI was 26.5 (23.9, 30.8) kg/m² (<i>p</i> < 0.001). The mean (SD) weight gain observed was 7.2 (6.2) kg over a mean (SD) disease duration of 41 (22.5) months. Median PWG was 8.8% (4.3%, 17%). There was a significantly reduced QoL in all comparable domains against general population normative data. PWG was associated with "cosmetic complaints" (odds ratio = 1.11, <i>p</i> = 0.008 via logistic regression; b = 0.47, <i>p</i> = 0.022, q (adjusted p) = 0.033 via GLM) and "tiredness and overall QoL" (b = 0.62, <i>p</i> = 0.011, q = 0.017), but not with the "anxiety and depressivity" domains (b = -0.005, <i>p</i> = 0.661). <b><i>Conclusions:</i></b> Our study suggests that weight gain after treatment of hyperthyroidism is associated with a large adverse effect on QoL, with reduced scores on appearance, combined "tiredness and overall QoL" domains of the ThyPRO questionnaire. Management of weight change upon treatment of hyperthyroidism merits further clinical attention and research.