Evaluation of the difference between mean corpuscular haemoglobin concentration and mean cellular haemoglobin concentration in canine complete blood count assessed with an automated haematology analyser.

Abstract

OBJECTIVES: The study aimed (a) to establish the reference interval for Δmean corpuscular haemoglobin concentration-mean cellular haemoglobin concentration in healthy dogs by ADVIA 2120 haematology analyser, (b) to identify the causes of increased Δmean corpuscular haemoglobin concentration-mean cellular haemoglobin concentration in both healthy and diseased canine samples and (c) to establish a cut-off value to prompt further diagnostic evaluations by practitioners. MATERIALS AND METHODS: A retrospective study was conducted evaluating the medical records of dogs referred to a Veterinary University Hospital. Healthy dogs were prospectively included to establish reference interval for complete blood count variables comprising Δmean corpuscular haemoglobin concentration-mean cellular haemoglobin concentration. Complete blood count reports of dogs who had both complete blood count and biochemistry performed concurrently were included. Complete blood counts were performed within 2 hours of sample collection, and biochemical analyses were carried out on serum samples within 12 hours. The macroscopic sample alterations were retrieved, including haemolysis, icterus, lipaemia and their severity. RESULTS: Reference interval for Δmean corpuscular haemoglobin concentration-mean cellular haemoglobin concentration was established and ranged from -1.70 to 2.20 g/dL (90% confidence interval of the upper limit 1.92 to 2.50). The Δmean corpuscular haemoglobin concentration-mean cellular haemoglobin concentration was significantly increased in lipaemic and haemolytic samples and significantly correlated with their severity. The frequency of samples with increased Δmean corpuscular haemoglobin concentration-mean cellular haemoglobin concentration (≥2.5 g/dL) was significantly higher in lipaemic and haemolytic samples and in patients undergoing corticosteroid therapy or affected by Cushing's syndrome. CLINICAL SIGNIFICANCE: An increase in Δmean corpuscular haemoglobin concentration-mean cellular haemoglobin concentration in dogs is often associated with macroscopic sample alterations, mainly due to lipaemia, haemolysis, or both. When a Δmean corpuscular haemoglobin concentration-mean cellular haemoglobin concentration value of >2.5 g/dL is noted, laboratories and practitioners should carefully evaluate the samples for any evidence of haemolysis or lipaemia.