On lupus, vitamin D and leukopenia.

BACKGROUND: Immune regulation is among the noncalcemic effects of vitamin D. So, this vitamin may play a role in autoimmune diseases such as systemic lupus erythematosus (SLE).

OBJECTIVES: To study the prevalence of vitamin D deficiency in SLE and its association with clinical, serological and treatment profile as well as with disease activity.

METHODS: Serum OH vitamin D3 levels were measured in 153 SLE patients and 85 controls. Data on clinical, serological and treatment profile of lupus patients were obtained through chart review. Blood cell count and SLEDAI (SLE disease activity index) were measured simultaneously with vitamin D determination.

RESULTS: SLE patients have lower levels of vitamin D than controls (p=0.03). In univariate analysis serum vitamin D was associated with leukopenia (p=0.02), use of cyclophosphamide (p=0.007) and methotrexate (p=0.03). A negative correlation was verified with prednisone dose (p=0.003). No association was found with disease activity measured by SLEDAI (p=0.88). In a multiple regression study only leukopenia remained as an independent association (B=4.04; p=0.02). A negative correlation of serum vitamin level with granulocyte (p=0.01) was also found, but not with lymphocyte count (p=0.33).

CONCLUSION: SLE patients have more deficiency of vitamin D than controls. This deficiency is not associated with disease activity but with leucopenia (granulocytopenia).