Effects of vitamin D replacement combined with Graves' disease therapy: a retrospective cohort study.

Baseline serum vitamin D levels in Graves' disease patients were significantly lower than in healthy controls.

• GD patients had mean baseline VitD of 16.1 ± 9.9 ng/mL compared to 22.2 ± 8.5 ng/mL in controls (p < 0.005)
• Study included 40 GD patients and 37 healthy controls
• Vitamin D measured as 25-hydroxy [25(OH)] vitamin D3

Vitamin D replacement therapy significantly increased serum vitamin D levels in the replacement group after three months.

• Mean VitD levels increased from 14.6 ± 8.3 ng/mL at baseline to 40.4 ± 17.2 ng/mL after three months (p < 0.001)
• The replacement group received antithyroid treatment plus VitD replacement (n = 22)
• The nonreplacement group received antithyroid treatment only (n = 18)

Both the replacement and nonreplacement groups showed significant improvement in thyroid hormone levels after three months of antithyroid treatment.

• A significant increase in serum TSH levels was observed in both groups at the end of three months
• Significant decreases in serum fT3 and fT4 levels were observed in both replacement and nonreplacement groups
• Changes in thyroid hormone levels occurred regardless of whether VitD replacement was administered

Vitamin D replacement had no significant effect on serum TSH, fT3, or fT4 levels compared to antithyroid treatment alone.

• No significant difference in TSH, fT3, or fT4 levels was found between the replacement and nonreplacement groups
• VitD replacement did not appear to accelerate normalization of thyroid hormone levels
• Authors noted these results need confirmation with larger patient numbers and longer follow-up periods

There was no significant difference in serum thyroid receptor antibody levels between the vitamin D replacement and nonreplacement groups.

• Thyroid receptor antibody (TRAb) levels were compared between the two GD treatment groups
• No significant difference in TRAb levels was detected between the replacement and nonreplacement groups
• This suggests VitD replacement did not meaningfully affect the autoimmune component of Graves' disease over the three-month study period