Validation and determination of a reference interval for canine HbA1c using an immunoturbidimetric assay.

BACKGROUND

Hemoglobin A1c (HbA1c) provides a reliable measure of glycemic control over 2-3 months in human diabetes mellitus. In dogs, presence of HbA1c has been demonstrated, but there are no validated commercial assays.

OBJECTIVE

The purpose of the study was to validate a commercially available automated immunoturbidimetric assay for canine HbA1c and determine an RI in a hospital population.

METHODS

The specificity of the assay was assessed by inducing glycosylation in vitro using isolated canine hemoglobin, repeatability by measuring canine samples 5 times in succession, long term inter-assay imprecision by measuring supplied control materials, stability using samples stored at 4°C over 5 days and -20°C over 8 weeks, linearity by mixing samples of known HbA1c in differing proportions, and the effect of anticoagulants with paired samples. An RI was determined using EDTA-anticoagulated blood samples from 60 nondiabetic hospitalized animals of various ages and breeds. Hemoglobin A1c was also measured in 10 diabetic dogs.

RESULTS

The concentration of HbA1c increased proportionally with glucose concentration in vitro. For repeat measurements, the CV was 4.08% (range 1.16-6.10%). Samples were stable for 5 days at 4°C. The assay was linear within the assessed range. Heparin- and EDTA-anticoagulated blood provided comparable results. The RI for HbA1c was 9-18.5 mmol/mol. There was no apparent effect of age or breed on HbA1c. In diabetic dogs, HbA1c ranged from 14 to 48 mmol/mol.

CONCLUSIONS

The assay provides a reliable method for canine HbA1c measurement with good analytic performance.