Evaluation of reticulocyte hemoglobin content (RETIC‐HGB) for the diagnosis of iron‐limited erythropoiesis in cats

• Published in: Veterinary clinical pathology Vol. 49; no. 4; pp. 557 - 566
• Main Authors: Keiner, Miriam, Fuchs, Jannika, Bauer, Natali, Moritz, Andreas
• Format: Journal Article
• Language: English
• Published: United States Wiley Subscription Services, Inc 01.12.2020
• Subjects: ADVIA 2120; Anemia, Iron-Deficiency - blood; Anemia, Iron-Deficiency - diagnosis; Anemia, Iron-Deficiency - veterinary; Animals; Case-Control Studies; Cat Diseases - blood; Cat Diseases - diagnosis; Cats; Erythrocyte Count - veterinary; Erythropoiesis; feline; Female; Hematocrit - veterinary; hematology; Hemoglobin; Hemoglobins - analysis; Iron; Male; ProCyte Dx; reference interval; Reticulocytes - chemistry; hematology; feline; ProCyte Dx; ADVIA 2120; reference interval
• ISSN: 0275-6382; 1939-165X
• DOI: 10.1111/vcp.12925

Background Decreased reticulocyte hemoglobin content (CHr) (Siemens ADVIA 2120) reflects iron‐limited erythropoiesis (ILE). RETIC‐HGB (IDEXX ProCyte Dx) is a novel marker of ILE for veterinary use. Objectives We aimed to evaluate reference intervals (RIs) and the utility of RETIC‐HGB and CHr in the diagnosis of feline ILE. Materials and Methods RIs were established in 59 healthy cats. Intra‐assay coefficients of variation (CVs) and correlations between RETIC‐HGB and CHr were assessed. Two hundred and seventy‐five cats were classified as having ILE or not based on low plasma iron or low transferrin saturation along with anemia and/or altered RBC indices. CHr, RETIC‐HGB, and serum amyloid A (SAA) were compared between the groups. The sensitivity and specificity of RETIC‐HGB and CHr to diagnose ILE were analyzed to determine the RI lower limits. Results RIs for RETIC‐HGB and CHr were 12.5‐18.0 and 14.0‐19.9 pg, respectively. The CV was 3% for both variables. RETIC‐HGB and CHr were moderately correlated (rs = 0.59) with a bias of −1.2 picograms (pgs). Twenty of the 275 cats were classified as having ILE. Compared with non‐ILE cats, ILE cats had significantly lower median RETIC‐HGB (14.3 vs 15.2 pg, P = .0046) and mean CHr (14.7 vs 16.5 pg, P < .0001) values and significantly increased median SAA (44.6 vs 2.3 µg/dl, P < .0001) values. Using the lower RI limits resulted in a low sensitivity and relatively high specificity to diagnose ILE in cats. Conclusions ILE was characterized by decreased CHr and RETIC‐HGB; however, sensitivity was low. The moderate correlation between RETIC‐HGB and CHr is likely due to species differences and different methodology.