Association of Vitamin D and secondary hyperparathyroidism with anemia in diabetic kidney disease.

Introduction: Anemia is common in Chronic Kidney Disease (CKD) and diabetes is a major leading risk factor for it. In Diabetic Kidney Disease (DKD), it worsens more, which further increases cardiovascular morbidity and mortality. Despite of adequate iron stores anemia persist, which may be due to impaired iron release from body stores that is unable to meet the demand for erythropoiesis (also called reticuloendothelial cell iron blockade). High parathyroid hormone (PTH) along with vitamin D, may be attributable for anemia.

Methods: A cross-sectional study of 150 advanced (Stage 4 & 5) pre dialyzed DKD patients (GFR <30ml/min/1.73 m2), aged 40-70 years were included over a period of 1 year. Any other concomitant illness/ drugs leading to anemia were excluded. Serum samples were collected and urea, creatinine, hemoglobin, iron profile, vitamin D, iPTH, uric acid, calcium, phosphorous and albumin levels were measured. A data base was constructed on Microsoft Excel 2007 and statistical analyses were performed using the SPSS software version 20.0 (IBM, NY, USA).

Results: Stage 5 DKD had more pronounced anemia compared to stage 4 DKD ( P < 0.001). Hemoglobin (Hb) was inversely correlated with iPTH (r = -0.74, P < 0.001) and was associated with vitamin D deficiency (r = 0.51, P < 0.001) but not with serum ferritin. DKD patients with low eGFR (r = -0.6, P < 0.001), vitamin D (r = -0.43, P < 0.001) and serum calcium (r = -0.37, P < 0.001) had higher iPTH. Secondary hyperparathyroidism (beta=-0.005; P < 0.001) and Vitamin D (beta=0.053; P < 0.01) were strong predictor for Hb while parameters of iron profile was not statistically significant.

Conclusion: An efficient control of PTH hypersecretion is therefore required to achieve a better management of anemia as well as mineral metabolism in DKD patients.