Please do read even if your background and interests are hypothyroidism.
Thyroid. 2019 Aug 2. doi: 10.1089/thy.2018.0731. [Epub ahead of print]
Patients treated for hyperthyroidism are at increased risk of becoming obese: findings from a large prospective secondary care cohort.
Torlinska B1, Nichols L2,3, Mohammed MA4, McCabe C5, Boelaert K6,7.
Author information
1 University of Birmingham, Institute of Applied Health, Occupational Health Building, Edgbaston, Birmingham, Birmingham, West Midlands, United Kingdom of Great Britain and Northern Ireland, B15 2TH; b.torlinska@bham.ac.uk.
2 University of Birmingham, Institute of Applied Health Research, Birmingham, United Kingdom of Great Britain and Northern Ireland.
3 University of Warwick, Department of Statistics, Coventry, United Kingdom of Great Britain and Northern Ireland; L.Nichols@bham.ac.uk.
4 University of Bradford, 1905, Faculty of Health Sciences, Bradford, West Yorkshire, United Kingdom of Great Britain and Northern Ireland; m.a.mohammed5@bradford.ac.uk.
5 University of Birmingham, Institute of Metabolism and Systems Research, Birmingham, United Kingdom of Great Britain and Northern Ireland; c.j.mccabe.med@bham.ac.uk.
6 University of Birmingham, Institute of Metabolism and Systems Research, Birmingham, United Kingdom of Great Britain and Northern Ireland.
7 Birmingham Health Partners, Centre for Endocrinology, Diabetes and Metabolism, Birmingham, United States; k.boelaert@bham.ac.uk.
Abstract
BACKGROUND:
The most commonly reported symptom of hyperthyroidism is weight loss; successful treatment increases weight. Weight gain faced by patients with hyperthyroidism is widely considered as a simple re-accumulation of premorbid weight, whereas many patients feel there is a significant weight "overshoot" attributable to the treatment. We aimed to establish if weight gain seen following treatment for hyperthyroidism represents replenishment of premorbid weight or "overshoot" beyond expected regain and, if there is excessive weight gain, whether this is associated with the applied treatment modality.
METHODS:
We calculated the risk of becoming obese (BMI>30 kg/m2) following treatment for hyperthyroidism by comparing body mass index (BMI) of 1373 patients with overt hyperthyroidism seen in a secondary care setting with the age- and sex-matched background population (Health Survey for England (2007-2009)). Next, we investigated the effect of treatment with antithyroid drug alone in regard to antithyroid drug with radioiodine therapy. We modelled the longitudinal weight data in relation to the treatment pathway to thyroid function and the need for long-term thyroxine replacement.
RESULTS:
During treatment of hyperthyroidism, men gained 8.0 kg (SD±7.5) and women 5.5 kg (±6.8). At discharge, there was a significantly increased risk of obesity in male (OR=1.7, 95%CI 1.3¬-2.2, P<0.001) and female (1.3, 1.2-1.5, P<0.001) patients with hyperthyroidism compared with the background population. Treatment with radioiodine was associated with additional weight gain (0.6 kg, 0.4-0.8, P<0.001), compared with antithyroid drug treatment alone. More weight gain was seen if serum TSH was markedly increased (TSH>10 mIU/L; 0.5 kg, 0.3-0.7, P<0.001) or free thyroxine was reduced (fT4 ≤10 pmol/L (0.8 ng/dl); 0.3 kg, 0.1-0.4, P<0.001) during follow-up. Initiation of levothyroxine was associated with further weight gain (0.4 kg, 0.2-0.6, P<0.001) and the predicted excess weight gain in radioiodine-induced hypothyroidism was 1.8 kg.
CONCLUSIONS:
Treatment for hyperthyroidism is associated with significant risks of becoming obese. Radioiodine treatment and subsequent development of hypothyroidism were associated with small but significant amounts of excess weight gain compared with antithyroid drugs alone. We advocate that the discussion over the weight "overshoot" risk forms part of the individualised treatment decision making process.
PMID: 31375059
DOI: 10.1089/thy.2018.0731