High- vs. routine-dose vitamin D3 in severe lupus on pulse methylprednisolone: a randomized, double-blind, placebo-controlled clinical trial.

INTRODUCTION/

OBJECTIVES

This study evaluated high- vs. routine-dose vitamin D3 in severe SLE patients on high-dose glucocorticoids, an underrepresented group in research.

METHODS

In a randomized, double-blind, placebo-controlled trial, 40 SLE inpatients receiving intravenous pulse methylprednisolone were assigned to "high-dose" (HD) (100,000 IU of vitamin D3 plus 7000 IU weekly, n = 20) or "routine-dose" (RD) vitamin D3 group (placebo plus 7000 IU weekly, n = 20) for 24 weeks. Changes in disease activity were assessed from baseline to study end.

RESULTS

Baseline SLEDAI scores were comparable between the HD group (median 19) and the RD group (median 14.5; p = 0.230). After 24 weeks, the HD group had a significantly greater increase in 25OHD concentrations (median 15.4 ng/ml) compared to the RD group (median 8.0 ng/ml; p = 0.028). No difference in SLEDAI scores was observed; however, there was a trend toward a greater ΔC4 increase in the HD group (7.38 vs. 3.27, p = 0.093). Δ25OHD showed positive correlations with disease activity markers. ROC analysis identified Δ25OHD cutoffs of 12.9 ng/ml (AUC = 0.741) for C3 and 11.7 ng/ml (AUC = 0.757) for C4 normalization, indicating that exceeding these may improve complement normalization.

CONCLUSIONS

Although SLEDAI scores did not differ between groups, high-dose vitamin D3 led to greater increases in 25OHD levels and showed trends toward improved serological markers. These exploratory findings suggest potential biological effects and support the safety and feasibility of high weekly doses (up to 100,000 IU), warranting further investigation in severe SLE.