Background: Vitamin D deficiency is prevalent in chronic kidney disease(CKD) patients, and has been reported to be associated with the risk of insulin resistance, albuminuria and cardiovascular disease, which is the major cause of mortality in CKD patients. We purposed to investigate the prevalence of 25-OHD deficiency and association with insulin resistance, proteinuria, and other indicators of arterial stiffness and endothelial function in renal transplant recipients.Patient and Method: Cross-section study of 95 our renal transplant patients with mean age of 48±10(25-70) years, and mean posttransplantation months of 103±53(15-201) was performed during November and December in 2007. We compared Insulin resistance (HOMA-IR), the prevalence of proteinuria (random urine protein-creatine ratio ≥ 0.2mg/mg), the brachial artery pulse wave velocity(PWV), flow-mediated vasodilation(FMD),ankle brachial index(ABI) and common carotid intima-media thickness(IMT) between 25-OHD deficiency (≤30ng/ml, N=19) and normal control group (>30ng/ml, N=76). Results: Mean 25-OHD(ng/ml) was 40.2±12.6 and 19 (20%) have 25-OHD deficiency. The prevalence of proteinuria was significantly higher in 25-OHD deficiency (47.4% vs.19.7%, p=0.019)than in normal 25-OHD. Vitamin D deficiency is a significant risk factor of proteinuria, independent of age, posttransplant month, gender, and BMI (OR= 3.93, P=0.03). No statically significant association of vitamin D deficiency with insulin resistance, PWV, ABI,and carotid IMT was observed. However, there was a trend that decreased FMD(6.73±3.66 % vs. 7.38±5.48%, p=0.19), increased PWV(15.00±3.23 m/s vs. 13.88±2.08m/s, p=0.07) in 25-OHD deficiency group. Conclusion: we concluded that 25-OHD deficiency is not uncommon and is significantly associated with an increased prevalence of proteinuria in renal transplant recipients. However, we failed to revealed that 25-OHD deficiency are associated with insulin resistance and arterial stiffness in kidney transplant recipients. Additional studies are needed to clarify the causal relationship of vitamin D with proteinuria and determine whether vitamin D therapy prevents or improves proteinuria, or markers of kidney and cardiovascular risk.
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