Iron Indices in Chronic Kidney Disease in the National Health and Nutritional Examination Survey 1988-2004

Background and objectives: Anemia is a common and early complication of nondialysis chronic kidney disease (CKD). One contributing factor is iron deficiency, which may be particularly problematic during erythropoietin replacement therapy. The aim of this study was to examine the prevalence of iron deficiency in nondialysis CKD. Design, setting, participants, & measurements: The National Health and Nutritional Examination Survey (NHANES) data for NHANES 111 (1988 to 1994) and subsequent NHANES 2-yr datasets, 1.999 to 2001), 2001 to 2002, and 2003 to 2004 were analyzed for individuals >18 yr old. Results: It was found that low levels of iron tests [either serurn ferritin < 100 ng/ml or transferrin saturation (TSAT) < 200%] were present in most patients with reduced creatinine clearance (CrCI). The percentage of low iron tests was higher among women than men, present in 57.8 to 58.8% of men and 69.9 to 72.8%, of women (P < 0.001). With declining levels of CrCI, in women, TSAT levels decreased, whereas, surprisingly, serum ferritin tended to progressively increase. The percentage of anemic subjects increased progressively with declining quartiles of TSAT but was unrelated to serum ferritin quartiles. Conclusions: It was found that low levels of iron tests, following National Kidney Foundation/Kidney Disease Outcomes Quality Initiative guidelines (either serum ferritin < 100 ng/ml or TSAT < 20%) were present in most patients with reduced CrCI.