Carboxyhemoglobin as a diagnostic and prognostic biomarker of hemolytic anemias in dogs

Abstract

Background: Endogenous production of carbon monoxide during hemoglobin metabolism leads to the formation of carboxyhemoglobin. Carboxyhemoglobin concentration is abnormally high in humans with hemolytic anemia (HA). Hypothesis: Measurement of carboxyhemoglobin concentration can discriminate HA from other forms of anemia. Animals: Twenty-seven dogs with HA (immune-mediated HA, n = 22; microangiopathic HA, n = 5), 27 dogs with non-HA (kidney disease, n = 14; immune-mediated thrombocytopenia, [n = 6]; miscellaneous, n = 7) and 24 nonanemic control dogs. Methods: Prospective cohort study. Carboxyhemoglobin quantification, a CBC and biochemistry profile were performed upon admission, and survival to hospital discharge and at 30 days were the measured outcomes. Groups were compared by the Mann-Whitney and Kruskal-Wallis tests. Receiver-operator characteristic (ROC) analyses were used to examine the predictive utility of carboxyhemoglobin for the diagnosis of HA in anemic dogs. Results: Carboxyhemoglobin (median [interquartile range]) differed between dogs with HA (7.7% [2.5%]) and non-HA (3.6% [1.05]; P