Vitamin D does not improve remission odds for adults with Graves’ disease
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Key takeaways:
- Vitamin D supplementation did not increase the likelihood for Graves’ disease remission compared with placebo.
- Nonsmokers were less likely to reach and sustain Graves’ disease remission with vitamin D.
Adults diagnosed with Graves’ disease who received vitamin D supplementation had a similar remission rate as people who did not receive a supplement, according to a study published in Thyroid.
In findings from a randomized controlled trial conducted in Denmark, participants who received vitamin D supplementation had a similar risk of failure to enter or sustain Graves’ disease remission than those who received placebo, and vitamin D supplementation was associated with an increased risk for failure of Graves’ disease remission for adults who where nonsmokers.
“We clearly showed that vitamin D does not improve the course of [Graves’] disease,” Diana Grove-Laugesen, MD, PhD, of the department of endocrinology and internal medicine at Aarhus University Hospital in Denmark, and colleagues wrote. “This result was consistent in all analyses and independent on baseline vitamin D status. Contrary to expectations, patients supplemented with vitamin D showed higher proportions of failure to enter and sustain remission and higher proportions of relapse of borderline statistical significance.”
Researchers conducted a double-blind, placebo-controlled, randomized controlled trial in which 278 adults aged 18 to 80 years diagnosed with Graves’ disease (mean age, 44 years; 79% women) were randomly assigned, 1:1, to 70 µg oral cholecalciferol or matching placebo daily. All participants received standard antithyroid drug therapy for the study duration. Relapse of Graves’ disease was defined as the recurrence of hyperthyroidism, repeat antithyroid drug treatment within 1 year of drug discontinuation, referral for radioactive iodine therapy or thyroid surgery, or an inability to stop antithyroid drug therapy within 2 years of the start of treatment. The trial’s primary outcome was the percentage of adults who failed to achieve and sustain Graves’ disease remission.
At baseline, 35% of participants had insufficient vitamin D with a 25-hydroxyvitamin D level of less than 50 nmol/L. In intention-to-treat analysis applying the best-case scenario, 42% of adults in the vitamin D group and 32% in the placebo group failed to enter and sustain remission. In analysis applying the worst-case scenario, 58% of the vitamin D group and 47% of the placebo group did not achieve and sustain remission. There was no difference in the risk for achieving and sustaining remission between the groups in either analysis. The findings were similar in per-protocol analysis as well as analyses limited to adults who were tapered off of antithyroid drug therapy during the study.
There were 217 nonsmokers and 61 who reported being current smokers in the study population. Researchers observed an interaction between intervention and current smoking (P = .02). Nonsmokers who received vitamin D had a higher risk of failure to enter and sustain Graves’ disease remission than nonsmokers receiving placebo (OR = 1.95; 95% CI, 1.1-3.45; P = .02). Nonsmokers receiving vitamin D supplements were more likely to have Graves’ disease relapse than nonsmokers receiving placebo (OR = 2.13; 95% CI, 1.06-4.26; P = .03). Among smokers, there was no difference in remission success or risk for relapse between the vitamin D and placebo groups.
The researchers noted the possible mechanism behind the interaction between smoking and vitamin D is unknown, and other studies revealed no interaction between smoking and vitamin D levels after supplementation.
“Whether smoking affects the response to vitamin D or whether our observation is a chance finding needs further scrutiny,” the researchers wrote.
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