Photoprotective behaviour and sunscreen use: impact on vitamin D levels in cutaneous lupus erythematosus

Background: Sun exposure of the skin, independent of dietary sources, may provide sufficient vitamin D in healthy individuals. A recent study of patients with cutaneous lupus erythematosus concluded that over 70% of them restrict their sun exposure. Methods: We recruited 52 patients with biopsy-proven cutaneous lupus erythematosus to establish whether they are deficient in 25-hydroxyvitamin D [25(OH)D]. We measured their serum 25(OH)D levels during summer months, investigated the effects of several variables on 25(OH)D levels and assessed the role of vitamin D supplementation. Results: An overall mean 25(OH)D level of 63.03 (+/- 23.3) nmol/l was obtained. Significantly low values (< 25 nmol/l) were recorded in two (3.8%) patients and concentrations below 75 nmol/l were found in 34 (65.4%) patients. 25(OH)D levels were significantly lower among sun avoiders and daily sunscreen users, while significantly higher values were found among those who took cholecalciferol (vitamin D3) supplements. Low values were recorded among those with renal disease despite supplementation with vitamin D3 in some cases. Conclusions: We suggest that patients with cutaneous lupus erythematous have suboptimal 25(OH)D levels, which are significantly raised by the addition of at least 400 IU/day of cholecalciferol. We recommend supplementation with an active vitamin D analogue in collaboration with a consultant nephrologist, for the subgroup of patients with renal disease.