Assessment of serum levels of vitamin D and tissue levels of vitamin D receptors in acanthosis nigricans

Background Acanthosis nigricans (AN) is a skin disorder characterized by symmetrical, thickened, dark plaques comprising hyperkeratosis and acanthosis. Vitamin D (VD) plays an important role in the regulation of skin proliferation and differentiation, and mediates its action by binding to specific vitamin D receptors (VDR) in the nuclei of target cells. Objective To measure the serum levels of VD and tissue levels of VDR in a group of Egyptian patients with AN in comparison to healthy controls, in order to shed more light on the possible relation between VD, VDR, and AN. Patients and methods This study included 25 AN patients and 25 age-matched and sex-matched healthy controls. Blood samples and skin biopsies were taken from all participants for the evaluation of serum VD, glucose, insulin, and tissue VDR levels. Results Serum VD and tissue VDR were significantly lower (P<0.001 for both), while serum insulin and homeostatic model for insulin resistance were significantly higher (P<0.001 and P=0.002, respectively) in patients than controls. Patients had a more deficient pattern of VD status than controls (P<0.001). There was a statistically significant positive correlation between serum VD and tissue VDR in patients (r=0.632, P=0.001). Conclusion The present study suggests a possible role for low serum VD and tissue VDR levels in causing AN, in genetically predisposed individuals.