Evaluation of reticulocyte hemoglobin content (RET-He) in the diagnosis of iron-deficient erythropoiesis in dogs.

Abstract

BACKGROUND: Reticulocyte hemoglobin content provided by the Siemens ADVIA (CHr) is an established marker of iron deficiency. The IDEXX ProCyte Dx hematology analyzer now provides a similar variable, reticulocyte hemoglobin equivalent (RET-He). OBJECTIVES: The objective was to evaluate RET-He and its diagnostic utility in dogs, and to calculate a cutoff value for diagnosing iron-deficient erythropoiesis (IDE). Furthermore, the prevalence of RET-He values below this cutoff value was established. METHODS: One hundred and seventy-one CBCs of healthy dogs were used to establish a RI. Stability of RET-He was evaluated by repeated measurements over 48 hours (n = 10). The 25-run coefficient of variation (CV) was calculated, and correlation and bias between measurements of RET-He and CHr were assessed (n = 190). A cutoff value for diagnosing IDE was calculated. The utility of RET-He in the detection of IDE was evaluated in 123 dogs. The prevalence of low RET-He values was assessed retrospectively in a multicenter study (2012-2014) under participation of 7 veterinary clinics. RESULTS: Reticulocyte hemoglobin equivalent with an RI of 22.2 to 28.6 pg was statistically stable over 48 hours (P = .10). The CV was 1.8%. A fair correlation (ρ = 0.74) between RET-He and CHr with a small bias of -0.6 pg was found. The cutoff value for diagnosing IDE was 20.9 pg (sensitivity: 85%; specificity: 99%). The prevalence of RET-He values below 20.9 pg was 10.3% (1084/10,553 dogs). CONCLUSIONS: RET-He on the ProCyte Dx is a precise screening tool in dogs to detect iron-deficient erythropoiesis.