A diagnostic study was conducted on 100 nondialysis patients who had CKD and anemia and were erythropoiesis-stimulating agent and iron naive. Bone marrow iron stores were evaluated by aspiration. Hemoglobin, transferrin saturation index (TSAT), and ferritin were measured at baseline and 1 month after 1000 mg of intravenous iron sucrose. Posttest predictive values for the erythropoietic response (>or =1-g/dl increase in hemoglobin) of peripheral and central iron indices were calculated.