Selenium Dosage for Graves Disease
Selenium supplementation at 200 μg daily is NOT recommended for treating Graves' hyperthyroidism itself, as the highest quality evidence shows no benefit on remission rates or quality of life. However, selenium 100 μg twice daily (200 μg total daily) may be considered specifically for patients with mild, active Graves' orbitopathy, where it has demonstrated clinical benefit 1.
Key Evidence-Based Recommendations
For Graves' Hyperthyroidism (Without Orbitopathy)
The 2026 GRASS trial—the most recent and highest quality randomized controlled trial—definitively showed that selenium supplementation (200 μg daily for 24-30 months) provided no benefit compared to placebo when added to standard antithyroid drug therapy 2. This large, multi-center, double-blind study of 430 patients found:
- No difference in remission rates (53.3% placebo vs 54.6% selenium; P=0.98)
- No improvement in quality of life on any measure
- No effect on thyroid receptor antibody levels
Therefore, selenium should not be routinely prescribed for Graves' hyperthyroidism management.
For Graves' Orbitopathy (Eye Disease)
The evidence diverges significantly when orbitopathy is present:
For mild, active Graves' orbitopathy:
- Dosage: 100 μg selenium twice daily (200 μg total) for 6 months 1
- The 2011 NEJM trial demonstrated significant benefits including:
- Improved quality of life (P<0.001)
- Reduced eye involvement (P=0.01)
- Slowed disease progression (P=0.01)
- Decreased Clinical Activity Score
- Effects persisted at 12-month follow-up
- No adverse events reported
For moderate-to-severe or inactive orbitopathy:
- Evidence is conflicting and less compelling
- Recent trials in selenium-sufficient populations show minimal to no benefit 3, 4
- Not routinely recommended
Clinical Algorithm for Selenium Use
Step 1: Assess the clinical presentation
- Graves' hyperthyroidism alone → Do not prescribe selenium 2
- Mild, active orbitopathy (CAS ≥3/7) → Consider selenium 200 μg daily 1
- Moderate-to-severe or inactive orbitopathy → Selenium not recommended 3, 4
Step 2: If prescribing for mild active orbitopathy
- Dose: 100 μg twice daily (or 200 μg once daily)
- Duration: 6 months minimum
- Monitor: Clinical Activity Score, quality of life, eye examination parameters
- Ensure patient is in a selenium-sufficient region (baseline selenium >70 μg/L)
Important Caveats
Geographic considerations: The effectiveness of selenium appears limited to selenium-deficient populations. Recent trials from selenium-sufficient areas (like South Korea) showed no benefit even for orbitopathy 3. Consider checking baseline selenium levels before supplementation.
Timing matters: Selenium should be initiated early in mild active orbitopathy, not after disease has progressed to moderate-severe or inactive stages 1, 4.
Not a substitute for standard therapy: Selenium is only adjunctive therapy. Standard treatments remain:
- Antithyroid drugs (methimazole preferred) for hyperthyroidism 5
- Corticosteroids for moderate-to-severe active orbitopathy 5
- Radioiodine or surgery as definitive therapy when indicated 6, 5
Avoid in radioiodine candidates with orbitopathy: Patients with orbitopathy choosing radioiodine therapy should receive corticosteroids (prednisone 0.4-0.5 mg/kg/day), not selenium, to prevent orbitopathy worsening 5.