Weight gain: Worth it for longer life
Compared with the background population, thyroidectomy was associated with an increased likelihood of developing obesity (BMI > 30 kg/m2) in both men (odds ratio, 1.56; P < .001), and women (OR, 1.27; P < .001), while radioiodine increased obesity risk in women (OR, 1.12; P < .001) but not in men (OR, 1.03; P = .55).
Among the women, those treated with antithyroid medications had an average 0.28 kg/m2 lower BMI, compared with the background population, and those treated with surgery had a 0.83 kg/m2 higher BMI. Both differences were significant (P < .001).
The BMI differences were not significant for radioactive iodine in women and for medications and radioactive iodine in men, although the men treated surgically also had a significantly higher BMI (1.09 kg/m2; P < .001).
“The patients on antithyroid drugs were lighter than we would expect. I think that’s ongoing hyperthyroidism. I strongly believe that ... to get rid of hyperthyroidism you have to make patients hypothyroid ... It’s really important that you get good control,” Dr. Boelaert commented.
Dr. Maraka, who is also endocrine section chief of the Arkansas Veteran’s Healthcare System, Little Rock, commented: “[Dr. Boelaert’s] concern is that the patients on antithyroid drugs are not adequately controlled, and we know very well that uncontrolled hyperthyroidism is associated with increased mortality and increased cardiovascular outcomes. This suggests that if patients are on antithyroid medications, they should at least be monitored very well.”
Regarding the possible cause of the increased mortality, if not cardiovascular, Dr. Maraka also pointed out that typically once antithyroid medications are stopped, about half of patients will stay in remission and the other half will return to hyperthyroidism.
“It might be that this kind of ‘yo-yo’ is what’s actually leading to the increased mortality, compared to patients who had definitive treatment and this problem was taken care of. This is speculation but it might be what we’re seeing,” Dr. Maraka observed.
The BMI differences worked out to a weight gain with surgery of approximately 2.1 kg (4.6 lb) for a woman with a height of 160 cm and 2.4 kg for 170 cm. Among men, those differences were 3.2 kg and 3.5 kg for heights of 170 cm and 190 cm, respectively.
Dr. Boelaert said, “I think we should discuss this with patients. They will say they don’t want to get fat, but the absolute weight gain is ... not that much.”
“I personally think that 2 kg is not a big price to pay to live longer. I hope that’s what we’ll be telling our patients in clinic in the next few years after we get this published.”
Dr. Boelaert and Dr. Maraka have reported no relevant financial relationships.
A version of this article first appeared on Medscape.com.