Objective: Assessment of serum 25-hydroxyvitamin D (25(OH)D) correlations with clinical parameters and evaluation of the efficacy of standard oral supplementation in systemic sclerosis (SSc) patients.
Methods: 154 SSc patients were recruited, in all seasons. Serum 25(OH)D concentrations were evaluated using LIAISON 25-OH (Diasorin, Italy). Medsger disease severity scale (DSS), nailfold videocapillaroscopy (NVC) and all instrumental exam contemplated by international guidelines were performed. Drug assumption, including oral colecalciferol, was evaluated. Non-parametric tests were used for statistical analysis.
Results: Average 25(OH)D serum concentration was 18.7 ±9 ng/ml (<20 classified as deficiency). A significant correlation was found with presence/absence of lung bi-basal fibrotic changes (16.1 ±8 ng/ml and 20 ±10 ng/ml, respectively; p = 0.04). Peripheral vascular (p = 0.03), kidney (p = 0.02), gastrointestinal (p = 0.05) Medsger's DSS parameters were found to correlate with 25(OH)D serum concentrations. No significant correlations were observed with digital ulcers incidence, strictly correlated to patterns of microangiopathy, defined at NVC analysis (p<0.0001). Interestingly, no effects of treatment with oral colecalciferol (Dibase 1,000 IU daily for at least 6 months) were found on 25(OH)D serum concentrations in treated (18.8 ±10 ng/ml) or untreated (18.7 ±9 ng/ml) SSc patients (p = 0.81). A significant difference was observed among seasonal 25(OH)D serum concentrations (winter: 14.6 ±7.8 ng/ml, spring: 17.2 ±7.9 ng/ml, summer: 21.43 ±10 ng/ml, autumn: 20.2 ±10 ng/ml; p = 0.032) in all patients.
Conclusion: Serum 25(OH)D deficiency was found to correlate with lung involvement, peripheral vascular, kidney and gastrointestinal Medsger's DSS parameters and with seasonality In SSc patients. Supplementation with oral colecalciferol was found not effective in increasing 25(OH)D serum concentrations. Therefore, for successful replacement, supra-physiological vitamin D3 doses or programmed UVB light exposure should be tested.