Iron status and hemoglobin level in chronic renal insufficiency

Much has been written on the important contribution of iron deficiency toward anemia and epoetin resistance among end-stage renal disease (ESRD) patients, but there are few studies of iron status among chronic renal insufficiency (CRI) subjects not yet requiring dialysis. The National Kidney Foundation-Kidney Disease Outcomes Quality Initiative (NKF-K/DOQI) Practice Guidelines recommend maintaining ferritin > or =100 ng/ml and transferrin saturation (TSAT) > or =20% to ensure adequate iron supply for erythropoiesis among patients with chronic kidney disease, whether or not they are dialysis-dependent. Analysis of the nationally representative data from the Third National Health and Nutrition Examination Survey (NHANES III 1988-1994) revealed that only a minority of anemic CRI subjects in the United States met these K/DOQI targets. For example, in the range of creatinine clearance (CrCl) 30 to 50 ml/min, less than one third of men with hemoglobin <12 g/dl and women with hemoglobin <11 g/dl had ferritin > or =100 ng/ml and TSAT > or =20%. In addition, TSAT levels above 20% were independently associated with higher hemoglobin levels. Such data raise the question whether the K/DOQI targets should be reevaluated. It is concluded that ferritin and TSAT targets derived from ESRD studies may not be applicable to subjects with CRI. Further studies are needed to guide optimization of iron status and hemoglobin level in the much larger CRI population.