Vitamin D Concentration in Patients After Heart and Kidney Transplantation

One of the main actions of vitamin D is bone mineralization regulation. Vitamin D is linked also to hypertension, diabetes, and cardiovascular disease. Vitamin D deficiency may result in osteomalacia, but its excess may result in bone calcium mobilization. Kidney transplant recipients are also at risk of hypovitaminosis D because of impaired graft function. The aim of the study was to assess vitamin D concentration in patients after heart and kidney transplantation. Ninety-eight stable heart transplant recipients were enrolled in the study; 80 kidney transplant recipients and 22 healthy volunteers served as controls. The laboratory tests, including parameters of 25-hydroxyvitamin D (calcidiol), were assayed using commercially available kits. Calcidiol deficiency (level below 10 ng/mL) was observed in 10% of the transplant group and in 55 % of the orthotopic heart transplant recipients (OHT). There was positive correlation between calcidiol concentration, hemoglobin, kidney function, and serum glucose in kidney transplant recipients. In OHT, vitamin D correlated with age, kidney function, hemoglobin, cholesterol, low-density lipoprotein cholesterol, and glucose. Both groups had similar kidney function. In both groups of patients with estimated glomerular filtration rate above 60 mL/min/1.72 m2, vitamin D was significantly higher. In OHT, vitamin D was higher in nondiabetic patients. In OHT in multivariate analysis, vitamin D was predicted in 24% by kidney function (beta = −0.30; P = .02) and hemoglobin concentration (beta = 0.25; P = .03). Vitamin D deficiency is more common in patients after heart transplantation than in kidney allograft recipients despite similar kidney function. The possible associations between the cardiovascular system and vitamin D merit further studies. •Vitamin D deficiency is highly prevalent among heart and kidney transplant recipients, especially at middle European latitudes, where the population suffers from lack of sunlight.•Patients on immunosuppression should avoid excessive sunlight exposure due to possible complications, including skin cancer.•Vitamin D deficiency is more common in patients after heart transplantation than in kidney allograft recipients despite similar kidney function and nearly equal calcium levels.•Calcidiol deficiency (