The results of the present study conducted in an HD population with sufficient iron stores and without anemia and hypervolemia indicates the following: (1) RDW is increased above normal reference range in ESRD patients, especially in the subgroup of patients with inflammation and malnutrition, (2) independent risk factors associated with RDW elevation were HD duration, CRP, interdialytic weight gain, and albumin levels, (3) RDW was positively correlated with HD duration, interdialytic weight gain, serum phosphate and CRP levels, and negatively correlated with serum albumin. This evidence concerns the gene ALB and nutritional deficiency disease.