Assessment of Circannual Rhythm in Plasma Level of Vitamin D Among Kidney Transplant Recipients in Mashhad

We studied plasma vitamin D level in 96 kidney transplant recipients and its circannual rhythm. Blood samples were tested for 25-hydroxy vitamin D, parathyroid hormone, creatinine, phosphate, and calcium levels in winter and summer 2014. The mean age was 41 years, and the mean transplant age was 6.1 years. Plasma levels of 25-hydroxy vitamin D were 18.0 ± 15.0 ng/mL in winter and 18.3 ± 14.7 ng/mL in summer (P = .64). Parathyroid hormone was inversely correlated with vitamin D level in both seasons (r = -0.044, P < .001). There was no relationship between vitamin D and other variables. Our study showed vitamin D deficiency is prevalent among kidney transplant recipients both in winter and summer. Also, vitamin D level did not rise from winter to summer. It is recommended to routinely check on kidney transplant recipients' vitamin D status.