PATTERN OF WEIGHT CHANGES FOLLOWING RADIOIODINE TREATMENT IN THAI PATIENTS WITH HYPERTHYROID GRAVES’ DISEASE

Abstract

OBJECTIVES
The average weight gain following radioiodine (RAI) treatment is reported at 5 to 7 kg. We determined the extent of weight gain and associated risk factors for becoming obese in a cohort of Thai patients with RAI-treated Graves’ disease (GD).

METHODOLOGY
A five-year retrospective study of RAI-treated GD patients at Theptarin Hospital was performed. Weights taken at initial presentation, RAI administration and follow-up were compared. The proportion and associated risk factors for weight gain ≥5% compared to weight at RAI administration were analyzed.

RESULTS
Between 2016 and 2020, 347 patients with GD (females 81.0%, mean age 34.0 ± 11.9 years, mean BMI 22. 9 kg/m2) were treated with RAI (median dose 20 mCi). Almost all (91.9%) had hypothyroidism. During the median follow-up of 25 months, 71.2% had a median weight change of +2.1 kg compared with weight at RAI administration, and +3.0 kg compared with premorbid weight. Men gained more weight (2.9 versus 2.0 kg, p=0.277). Those with obese class I (BMI 25.0 to 29.9 kg/m2) and class II (BMI ≥30.0 kg/m2) increased (25.7 to 28.3%, and 6.2 to 9.1%, respectively). Weight loss upon diagnosis of GD and before RAI administration were the only factors associated with weight gain ≥5%.

CONCLUSION
Weight gain post-RAI treatment is common, with a significant proportion eventually becoming obese. Discussion of the risk of weight gain and the need for early intervention with comprehensive weight management support should be done in patients at risk.