Hypovitaminosis D is a common complication of systemic sclerosis (SSc). Cytokines are key mediators of tissue damage and clinical dysfunction in SSc, and vitamin D levels may impact them. To assess vitamin D serum levels and their relationship to clinical characteristics and cytokine profiles in SSc patients. A case-control study with 50 SSc patients and 35 healthy non-matched controls was conducted. The chemiluminescence test was used to assess blood levels of 25(OH) vitamin D, and flow cytometry was used to determine serum concentrations of interleukin 2 (IL-2), IL-4, IL-6, IL-10, tumour necrosis factor, and interferon. Fourteen patients exhibited diffuse cutaneous SSc, with a mean age of 57.2 12.8 years, 94 percent of whom were female and 80 percent of whom were European ancestors. Despite more frequent vitamin D treatment in SSc patients, blood vitamin D levels were 23.9 8.5 ng/mL and 30.2 6.2 ng/mL in the control group. There were no significant correlations identified between vitamin D concentrations and cytokine levels. Serum IL-6 levels were substantially higher in SSc patients and associated with the modified Rodnan skin score.

Despite decreased vitamin D levels in SSc patients, no obvious relationship with any cytokine was seen. In SSc patients, serum IL-6 levels were considerably increased and were associated with the degree of skin involvement.