Reduced erythropoietin responsiveness to anemia in diabetic patients before advanced diabetic nephropathy

We often encounter diabetic patients with anemia in whom the causes of anem ia were not clearly identified despite differential hematologic studies. We therefore studied the clinical and biochemical characteristics of diabetic patients with anemia of uncertain cause and measured erythropoietin (Epo) concentrations in 35 diabetic subjects without significant diabetic renal d isease. Among 62 medical records of diabetic patients with anemia, showing no evidence of advanced diabetic nephropathy (creatinine clearance greater than or equal to 30 mg/kg/1.73 m(2)), the causes of the anemia were not abl e to be identified in 28 cases (45.2%). In addition, we enrolled 35 diabeti c patients with uncertain causes of anemia in order to evaluate the serum E po responsiveness to anemia, and compared levels to a group of non-diabetic subjects also with anemia. The serum Epo concentrations of diabetic patien ts (17.6 +/- 8.1 mIU/ml) were significantly lower than those of non-diabeti c patients with similar degree of decrease in hemoglobin concentrations (14 4.9 +/- 108.0 mIU/ml, P < 0.001). The hemoglobin concentrations of diabetic patients correlated with creatinine clearance (r = 0.34, P = 0.03), serum creatinine (r = -0.49, P = 0.003) and albumin excretion rate (r = -0.44, P = 0.009), but showed no relation to age, duration of diabetes, glycated hem oglobin, presence of retinopathy or neuropathy. We concluded that reduced E po responsiveness to anemia could explain the anemia present in diabetic pa tient but without advanced diabetic nephropathy. This may reflect early ren al interstitial damage. (C) 1999 Elsevier Science Ireland Ltd. All rights r eserved.