Assessment of iron-restricted erythropoiesis in chronic renal disease: evaluation of Abbott CELL-DYN Sapphire mean reticulocyte hemoglobin content (MCHr).

We studied the performance of mean reticulocyte hemoglobin content (MCHr), measured on Abbott CELL-DYN Sapphire analyzer for the detection of functional iron deficiency. Patients with anemia and with renal disease were prospectively selected from the outpatient population of our hospital, 512 subjects were studied. Diagnoses and other medical data were retrieved from the hospital information system. MCHr was measured using a CELL-DYN Sapphire hematology analyzer (Abbott Diagnostics). Standard laboratory and statistical tests were used. Receiver operating characteristic (ROC) analysis was used to establish the diagnostic performance of MCHr for detecting iron-restricted erythropoiesis, with transferrin saturation <20% as the gold standard. Patients in the iron deficiency anemia group all had a state of iron depletion and iron-restricted erythropoiesis (median MCHr 25.4 pg). Patients with anemia of chronic disease showed also low MCHr, median 27.6 pg, but not statistically different from the iron deficient group (p = .0585). Renal patients with iron restriction (n = 66) had significantly lower MCHr (p < .0001) than those receiving adequate iron supply (n = 100): median MCHr were 27.9 and 32.5 pg, respectively. ROC analysis gave sensitivity 84.4% and specificity 80.1% with area under curve 0.863 (95% CI 0.823-0.902) at an MCHr cut-off 30.0 pg. MCHr on CELL-DYN Sapphire has equivalent clinical performance for detecting absolute or functional iron deficiency in patients with chronic kidney disease as previously published for another type of analyzer.