Vitamin D supply in patients with rheumatic diseases in Poland - a pilot study

In rheumatic diseases, vitamin D supply is recommended as part of the prophylaxis and treatment of osteoporosis, especially in patients undergoing glucocorticoid therapy, but also due to its immunoregulatory and anti-inflammatory properties. We aimed to evaluate serum 25-hydroxyvitamin D [25(OH)D₃] levels in Polish patients with systemic sclerosis (SSc), systemic lupus erythematosus (SLE) and granulomatosis with polyangiitis (GPA), in relation to various clinical parameters, and to assess the initial range of doses for the purpose of further research.

112 patients (39 with SLE, 44 with SSc and 29 with GPA), referred to the Department of Rheumatology and Internal Medicine in Poznan, Poland, were enrolled in this retrospective study. Demographic and clinical data were collected, including 25(OH)D₃ serum levels, vitamin D supplementation doses and season of blood sampling.

Mean (SD) serum 25(OH)D₃ concentrations were 31 (19.4) ng/ml for SLE, 28.8 (12.5) ng/ml for SSc and 28 (15.2) ng/ml for GPA, and they did not significantly differ between the groups. Vitamin D levels below the optimal range were found in 43.8% of SLE, 65.9% of SSc and 72.4% of GPA patients. 80% of patients reported vitamin D intake, with a mean daily dose of 1398 IU for SLE, 1345 IU for SSc and 1689 IU for GPA. Vitamin D insufficiency and deficiency were frequent among patients with rheumatic diseases, independently of the diagnosis and season.

Patients with rheumatic diseases seem to require higher doses of vitamin D than recommended for the general population. The present results indicate the necessity to use higher initial doses of vitamin D in this group of patients (2000 to 4000 UI) and to maintain the dose of vitamin D regardless of the change of seasons.