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.