Iatrogenic hyperthyroidism does not promote weight loss or prevent ageing‐related increases in body mass in thyroid cancer survivors
Context Thyroid cancer survivors represent a unique population in which the potential long‐term effects of brief periods of intentional thyroid hormone withdrawal and/or prolonged periods of iatrogenic hyperthyroidism on body weight and body mass were evaluated.
Objectives The objectives of this study were to characterize body mass changes over several years in a cohort of thyroid cancer patients with iatrogenic hyperthyroidism and to compare these changes with the expected weight gain in age‐matched healthy control populations. We also evaluated the possibility that the method of preparation [thyroid hormone withdrawal (THW) vs recombinant human TSH (rhTSH)] for radioactive iodine remnant ablation may be associated with differences in body mass at the time of the final follow‐up.
Design/Setting/Patients/Interventions A retrospective review identified 153 patients with thyroid cancer who underwent total thyroidectomy at one major medical centre. Of the 153 patients, 143 also had radioactive iodine remnant ablation: 70 after THW and 73 after rhTSH.
Main Outcome Measures Change in weight and BMI at 1–2 and 3–5 years of follow‐up points were examined. Annualized weight variation within the cohort was compared with age‐matched population controls expressed in kilogram/year.
Results Significant weight gain was noted for the full cohort after 3–5 years of follow‐up as compared to baseline (76 ± 21 kg at baseline vs 79 ± 23 kg at 3–5 years of follow‐up, P < 0·01), which represented a 3·2% increase. Female and male patients with thyroid cancer experienced 0·46 and 0·94 kg/year gain in weight, respectively, which is similar or somewhat higher than previously published age‐matched population controls (ranging from 0·23 to 0·34 kg/year). When expressed as per cent change and comparing the final weight to the pre‐operative baseline, the rhTSH group experienced approximately a 1·7% increase in weight compared with the 3·9% increase seen with THW patients (P = 0·02). When expressed as kg/year change, the rhTSH cohort had 0·34 kg/year change compared with the 0·64 kg/year change seen in the thyroid hormone withdrawal patients (P = 0·02).
Conclusion In otherwise, healthy patients with differentiated thyroid cancer, significant weight gain occurred during the 3–5 years of follow‐up despite ongoing thyrotropin suppression. The data suggest that mild iatrogenic hyperthyroidism does not promote weight loss or prevent ageing‐related weight gain. Greater weight gain was seen in patients prepared for radioactive remnant ablation with THW than with rhTSH.
Document Type: Research Article
Affiliations: 1: Department of Medicine, Memorial Sloan Kettering Cancer, New York, NY 2: Department of Obstetrics and Gynecology, University of Colorado, Aurora, CO 3: Department of Endocrinology, Memorial Sloan Kettering Cancer, New York, NY, USA
Publication date: April 1, 2012