Effect of Vitamin D Supplementation on Graves' Disease: The DAGMAR Trial

Diana Grove-Laugesen, Eva Ebbehoj, Torquil Watt, Anne Lene Riis, Torben Østergård, Bjarke Johannessen Bruun, Jens Juel Christiansen, Klavs Würgler Hansen, Lars Rejnmark


Objective: Treatment options in Graves' disease (GD) are limited and do not target the underlying autoimmunity, and relapse rates following a course of antithyroid drug (ATD) reach 50%. Previous research has shown promising results for a role of vitamin D in GD. We aimed to investigate whether vitamin D reduces failure to enter and sustain remission in patients with GD treated with ATD. Design: A multicenter, double-blinded, randomized placebo-controlled trial comparing vitamin D 70 mcg once daily (2800 IU) or placebo. The intervention was given first as add-on to ATD treatment, maximally 24 months, and then for 12 months after ATD cessation. Inclusion period was from 2015 to 2017 and study completion by December 2020. Patients included were adults with a first-time diagnosis of GD treated with ATD. Exclusion criteria included pregnancy and glucocorticoid treatment. The primary endpoint was failure to enter and sustain remission defined as relapse of hyperthyroidism within 12 months after ATD cessation, inability to stop ATD within 24 months, or radioiodine treatment or thyroidectomy. Two hundred seventy-eight patients were included in the study, and 4 patients withdrew consent. No adverse effects were found. Results: Participants were aged 44 ± 14 years at enrollment and 79% were female. The risk of failure to enter and sustain remission was 42% [95% confidence interval (CI) 33-50%] in the vitamin D group and 32% [CI 24-40%] in the placebo group corresponding to a relative risk of 1.30 [CI 0.95-1.78]. Conclusions: Vitamin D supplementation did not improve the treatment of GD in patients with normal or insufficient vitamin D status. Thus, supplementation with high-dose vitamin D cannot be recommended for GD. Study registration: ClinicalTrials.gov NCT02384668.

Original languageEnglish
JournalThyroid : official journal of the American Thyroid Association
Issue number9
Pages (from-to)1110-1118
Number of pages9
Publication statusPublished - Sept 2023


  • Adult
  • Pregnancy
  • Humans
  • Female
  • Male
  • Treatment Outcome
  • Iodine Radioisotopes/therapeutic use
  • Graves Disease/diagnosis
  • Antithyroid Agents/therapeutic use
  • Vitamins/therapeutic use
  • Dietary Supplements
  • Vitamin D/therapeutic use
  • Recurrence


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