Introduction: The relationship between vitamin D deficiency and anemia has been evaluated in patients with CKD. However, there is no study examining this relationship in renal transplantation patients. In this study, we examined the relationship between Vitamin D levels and anemia in pediatric renal transplant patients.
Materials and Methods: Records of pediatric renal transplant recipients (aged 0-18 years), who were followed up for at least one year after renal transplantation, were examined retrospectively. Transplant age, donor type, immunosuppressive treatments, infection, rejection, graft loss status and complete blood count, serum iron (Fe), serum iron-binding capacity, ferritin, urea, creatinine, calcium, phosphorus, alkaline phosphatase, parathyroid hormone (PTH) values, and eGFR values were recorded. Anemia was defined as hemoglobin level below 11 g/dl; vitamin D deficiency defined as 25 (OH)-D values were <20ng/ml. Patients were grouped according to their 25 (OH)-D levels (<20ng/ml; group 1, 20-30 ng/ml; group 2, >30 ng/ml; group 3).
Results: Seventy-five patients were included in to study. The mean age of patients was 11.8±4.9 years (34 girls and 41 boys). There were 41 patients (54.7%) in group 1, 24 patients (32%) in group 2, and 10 patients (13%) in group 3. The groups were similar in terms of gender, transplantation age, donor type, immunosuppressive therapy, and follow-up times. Mean hematocrit and ferritin levels were found to be significantly lower in group 1 when compared with the other groups (p<0.05). However, there was no significant difference between the groups in terms Hgb, serum Fe, transferrin saturation and serum Ca, P, ALP, and PTH values (p>0.05). Serum Fe levels were low in patients with vitamin D deficiency, but no statistically significant difference was found. The groups were similar in terms of infection, rejection, graft loss, and 3rd-year eGFR (p>0.05). 
Anemia was present in 20(26.6%) patients and 94% of these had Vitamin D deficiency or insufficiency. In 7(12.7%) patients without anemia Vitamin D levels were within normal limits, while only 1(5.6%) of patients with anemia had normal Vitamin D levels. Vitamin D levels were found to be lower in patients with anemia. PTH and eGFR values were similar in with and without anemia group.
Conclusion: Vitamin D deficiency is a treatable risk factor for graft loss and mortality in patients with persistent anemia after renal transplantation Vitamin D levels of the patients should be followed up and if deficiency is detected, it should be treated. Further studies are needed on the relationship between Vitamin D level and anemia in renal transplant patients.