Validation, reference intervals and overlap performance of a new commercially available automated capillary electrophoresis assay for the determination of the major fraction of glycated haemoglobin (HbA1c) in dogs

Establishment of a feline glycated hemoglobin reference interval for a novel dried-blood-spot assay and the effects of anemia on assay results

BACKGROUND

Glycated hemoglobin A1c (HbA1c) reflects long-term (months) glycemic control and has been previously investigated as a monitoring and diagnostic tool in diabetic cats. However, a standardized, reliable, and globally available test and reference intervals (RIs) have not been established. A novel dried-blood-spot card system (A1Care, Baycom Diagnostics) allows for easy collection and evaluation of HbA1c levels in feline patients.

OBJECTIVE

We aimed to establish an RI for HbA1c values in healthy adult cats using the A1Care (Baycom Diagnostics) dried-blood-spot card system.

METHODS

Forty-one healthy client-owned adult cats were enrolled in this study. The RI for HbA1c was calculated according to the recommendation of the American Society for Veterinary Clinical Pathology.

RESULTS

The A1Care HbA1c RI for cats was determined to be 1.9%-3.1%. In healthy cats, A1Care HbA1c values were positively correlated with age (Spearman rho = 0.4 [95% CI 0.1 to 0.6], P = 0.01). In 50% of anemic cats, the A1Care HbA1c value was above 3.1%. There was a weak negative correlation between the A1Care HbA1c value and PCV (Spearman rho = -0.4 [95% CI -0.6 to -0.1]).

CONCLUSIONS

This study established an RI for HbA1c in healthy adult cats similar to previously reported RIs. Future clinical studies are necessary to substantiate that this RI can differentiate diabetic from nondiabetic cats. Further long-term clinical studies will be valuable to determine if HbA1c values can be used as a screening test for prediabetes in cats.

Diagnostic performance of glycated haemoglobin (HbA1c) for diabetes mellitus in dogs

The objective of this study was to determine the diagnostic performance of glycated haemoglobin (HbA1c) for canine diabetes mellitus (DM) and compare it with that of serum fructosamine. Aliquots of blood samples collected for diagnostic purposes from adult dogs were used. HbA1c was measured using a previously validated capillary electrophoresis assay. The dogs were allocated into four groups: (1) DM; (2) hyperadrenocorticism (HAC); (3) long-term corticosteroid therapy (CST); and (4) various chronic diseases (VD). In total, 88 dogs were included as follows: DM (n = 11), HAC (n = 10), CST (n = 14), and VD (n = 53). Fructosamine was measured in all four groups as follows: DM (n = 6), HAC (n = 7), CST (n = 9), and VD (n = 42). Median (range) serum glucose concentration was higher (P < 0.001) in the DM group (22.8 mmol/L; range, 15.6-29.3 mmol/L) compared to HAC (5.9 mmol/L; range, 4.2-6.8 mmol/L), CST (5.6 mmol/L; range, 4.3-23.3 mmol/L), and VD (5.5 mmol/L; range, 4.1-9.4 mmol/L) groups. Mean (± standard deviation) HbA1c was higher (P < 0.001) in the DM group (6.3% ± 1.5%) compared to HAC (1.9% ± 0.5%), CST (1.7% ± 0.5%), and VD (1.9% ± 0.5%) groups. All diabetic dogs and none of the other dogs had HbA1c levels above the cut-off value for DM (3.3%), indicating an accuracy of 100% in diagnosing DM. Significant differences (P < 0.01) were observed in median fructosamine between the DM group (389 μmol/L; range, 348-865 μmol/L) and the HAC (306 μmol/L; range, 167-348 μmol/L) and the VD (316 μmol/L; range, 189-500 μmol/L) groups. Fructosamine had an accuracy of 84.4% for the diagnosis of DM. When used for the diagnosis of canine DM, HbA1c measured with this specific assay had excellent diagnostic accuracy and was superior to serum fructosamine.

Association of platelet indices with glycemic status in diabetic dogs

We investigated the platelet count (PLT), mean platelet volume (MPV), and plateletcrit (PCT) in dogs with type 1 diabetes mellitus (DM) compared to healthy controls, and their association with the major fraction of glycated hemoglobin (HbA1c). Blood samples from 33 clinically healthy dogs and 14 newly diagnosed diabetic dogs were included. CBCs were performed with the Advia 120; HbA1c was determined using a validated assay (Capillarys 2 flex-piercing; Sebia). Median [range] PLT and PCT were significantly higher (p = 0.040 and p = 0.010, respectively) in diabetic dogs (434 [176-987] × 10⁹/L and 0.60 [0.26-1.22]%, respectively) compared to healthy dogs (297 [223-671] × 10⁹/L and 0.35 [0.24-0.87]%, respectively]. Thrombocytosis was observed in 6 of 14 (43%) diabetic dogs. The median MPV was not significantly different (p = 0.114) between the diabetic (13.6 fL, 10.1-22.6 fL) and healthy dogs (11.9 fL, 8.6-19.1 fL). A significant, albeit weak, correlation was detected between HbA1c and PLT (rho = 0.298, p = 0.042) and PCT (rho = 0.340, p = 0.019), but no significant correlation was found with MPV (rho = 0.199, p = 0.180). Canine DM was associated with increased PLT and PCT, which was correlated with glycemic status. Our findings suggest dysregulated megakaryopoiesis in diabetic dogs, but this should be confirmed by large-scale studies, and the clinical implications should be investigated.

Relationship between HbA1c, fructosamine and clinical assessment of glycemic control in dogs

Background

Serum fructosamine is a routine test used for clinical monitoring of diabetes mellitus (DM) but the usefulness of HbA1c for this purpose has not been extensively studied.

Hypothesis

The study aimed to compare the ability of blood HbA1c and serum fructosamine tests to correctly classify DM control determined using a clinically-based assessment.

Animals

28 client-owned dogs with naturally-occurring diabetes mellitus.

Methods

Cross-sectional observational study. Ability of fructosamine and HbA1c tests to classify diabetes control in dogs was determined.

Results

Clinical assessment classified 50% of dogs as having good diabetic control and 82% as having acceptable diabetic control. Analysis using Cohen’s kappa test showed that agreements between fructosamine and HbA1c results and the clinical assessment ranged from poor to fair. Fructosamine and HbA1c results from each dog showed a moderate correlation. Overall, the HbA1c test showed the best agreement with the clinical assessment when diabetes control was considered either acceptable or unacceptable, although the strength of agreement was considered fair (kappa = 0.27).

Conclusions and clinical importance

The HbA1c concentration was found to be more consistent with clinical evaluation of diabetes control than was the serum fructosamine concentration. The HbA1c level is a useful tool for assessment of glycemic status in diabetic dogs but should be used alongside other tests for outpatient monitoring of clinically stable diabetic dogs.

The effect of age and sex on glycated hemoglobin in dogs

We investigated the effect of age and sex on canine glycated hemoglobin (HbA1c) using a validated capillary electrophoresis assay. Aliquots of EDTA blood samples collected for routine health checks were used. HbA1c was measured using the Capillarys 2 flex-piercing system (Sebia). We included 58 clinically and hematologically healthy, normoglycemic dogs (29 males, 29 females), allocated to 3 age groups: young (14 dogs <1-y-old), adult (31 dogs 1-7.9-y-old), and senior (13 dogs ≥8-y-old). The mean (± SD) HbA1c was not significantly different (p = 0.428) between the age groups (young: 1.68 ± 0.54%; adult: 1.59 ± 0.41%; senior: 1.80 ± 0.57%). The HbA1c was not significantly correlated with age (rho = 0.144, p = 0.280). The median (range) HbA1c was not significantly different (p = 0.391) between male [1.7% (0.5-2.5%)] and female [1.5% (1.0-2.7%)] dogs. Age and sex do not appear to affect canine HbA1c; however, a study of geriatric dogs would be needed to fully exclude an effect of age on HbA1c.

Characterization of Particle Size Distribution of Plasma Lipoproteins in Dairy Cattle Using High-Resolution Polyacrylamide Electrophoresis

Plasma lipoproteins play critical roles in energy metabolism and inflammation. Concentrations of high-density lipoproteins (HDL) are linked to reproductive outcomes and milk yields in dairy cattle. Low-density lipoproteins (LDL), which are enzymatically formed in the blood from very low-density lipoproteins (VLDL) following secretion by the liver, have been used as a surrogate marker of liver function due to the rapid influx of circulating VLDL into the lactating mammary gland. In humans, the composition of plasma lipoproteins is reflected in lipoprotein particle size distribution, and both of these parameters are highly predictive of disease development and related health outcomes. Bovine HDL are overall larger, less dense particles compared to human HDL. Lipoprotein particle size distribution in both health and disease is understudied in the bovine. We hypothesize that a more detailed analysis of lipoproteins could hold diagnostic and/or prognostic value in the study of dairy cattle health and production. In this study, we took the first steps in this characterization and used a high-resolution polyacrylamide gel electrophoretic assay to better define LDL and HDL at the subfraction level in Holstein cows at different stages of lactation. We extensively characterized the lipoprotein particle size distribution in healthy lactating dairy cattle. We identified subfractions of LDL that were prominent only in the dry period and subfractions of HDL that were highest in cows during mid-lactation. Use of this method could be informative in the study of multiple herds and management strategies, including longitudinal evaluation of animals and production parameters.

Effect of anaemia and erythrocyte indices on canine glycated haemoglobin

BACKGROUND

The major fraction of glycated haemoglobin (HbA1c) depends on blood glucose concentration and erythrocyte lifespan, and consequently erythrocyte indices may affect HbA1c; our objective was to study this effect in dogs.

METHODS

Blood samples from two (healthy and anaemic) age- and sex-matched, normoglycaemic populations were prospectively included. Advia 120 and Capillarys 2 flex-piercing were used for the haematological and HbA1c analyses, respectively.

RESULTS

Lower mean HbA1c was found in dogs with regenerative (n = 8, 0.88 ± 0.58%) and non-regenerative anaemia (n = 12, 1.36 ± 0.56%) compared to healthy ones (n = 40, 1.68 ± 0.48%); the difference was significant (p < 0.001) between the healthy dogs and those with regenerative anaemia. HbA1c was significantly correlated (p < 0.05) with red blood cell count (r = 0.506), haemoglobin (r = 0.474), haematocrit (r = 0.467), mean corpuscular volume (r = -0.289), mean corpuscular haemoglobin concentration (r = 0.284), red cell distribution width (r = -0.286) and reticulocytes (r_s = -0.542).

CONCLUSION

Anaemia, particularly if regenerative, can lower HbA1c. The significant correlation between HbA1c and erythrocyte indices likely reflects the effect of erythrocyte turnover on HbA1c.

Reference Interval of Hemoglobin A1c and Influence of Hematological Parameters on Its Serum Concentration in Dogs

HbA1c could be an alternative to fructosamine as a marker for glucose levels over a longer period. In this study, we calculated a reference interval for HbA1c in dogs and investigated the correlation of HbA1c with hemoglobin and different hematological parameters. In total, 110 blood samples from dogs were investigated. Significant negative correlations were found between HbA1c and erythrocyte count, hemoglobin concentration, as well as hematocrit. There was a tendency in the red cell distribution width. No significant correlation was found in the reticulocyte number and the erythrocyte indices. In conclusion, there is an association of different blood parameters with the HbA1c concentration, which have to be considered for the interpretation of HbA1c.

Comparison of serum fructosamine and glycated hemoglobin values for assessment of glycemic control in dogs with diabetes mellitus

OBJECTIVE

To evaluate the performance of 2 assays for measurement of serum fructosamine (SF) and glycated hemoglobin (HbA1c) values in dogs and to compare the usefulness of the 2 glycated proteins for assessment of glycemic control in dogs with diabetes mellitus (DM).

SAMPLE

Blood samples from 40 healthy dogs, 13 diabetic dogs, and 23 anemic normoglycemic nondiabetic dogs and results of 200 assessments of glycemic control in 46 diabetic dogs.

PROCEDURES

Colorimetric and immunoturbidimetric methods were used for measurement of SF and HbA1c values, respectively. Linearity and precision were determined. The usefulness of SF and HbA1c values for assessment of glycemic control was evaluated with a clinical scoring method used as the reference standard. Cutoff values obtained from receiver operating characteristic curves were used to identify the percentage of dogs correctly categorized by means of SF and HbA1c values.

RESULTS

Mean intra-assay and interassay coefficients of variation were 3.8% and 2.5%, respectively, for the SF assay, and 1.2% and 1.8%, respectively, for the HbA1c assay. Excellent linearity (R² > 0.99) was obtained for both assays. Values for SF and HbA1c were inversely correlated (r = -0.40 and -0.33, respectively) with clinical score and correctly indicated glycemic control in 99 of 200 (50%) and 88 of 200 (44%) assessments, respectively.

CONCLUSIONS AND CLINICAL RELEVANCE

The SF and HbA1c assays were precise, had good linearity, and appeared to be suitable for routine use in veterinary medicine. However, they performed poorly for classifying glycemic control in diabetic dogs.

Favorable outcome of pheochromocytoma in a dog with atypical Cushing's syndrome and diabetes mellitus following medical treatment: a case report

Background

Pheochromocytoma (PCC) has poor prognosis and adrenalectomy is hard to be performed, in case of caudal vena cava invasion. The long-term administration of phenoxybenzamine in PCC has not been reported in dogs.

Case presentation

A 14-year-old castrated male Poodle dog presented with an abdominal mass. On physical examination, hypertension, increased lens opacity, calcinosis cutis, generalized alopecia, and systolic murmur were observed. Serum chemistry and urinalysis profiles revealed hyperglycemia, hypercholesterolemia, elevated liver enzymes, and glucosuria. Abdominal ultrasonography showed a right adrenal mass with invasion of the caudal vena cava, which was cytologically diagnosed as suspected PCC. An adrenal mass (width × height × length, 28 × 26 × 48 mm³) was found on computed tomography and diagnosed as PCC with increased plasma metanephrines and normetanephrines. An adrenocorticotropin hormone stimulation test showed elevated adrenal hormones (androstenedione, estradiol, progesterone, and 17-OH progesterone) with normal cortisol, compatible with atypical Cushing’s syndrome. The dog was managed with trilostane, phenoxybenzamine, and insulin therapy. Glycosylated hemoglobin and fructosamine levels gradually decreased, and hypertension resolved. In the 10-month follow-up period, the liver enzymes levels gradually decreased, and the clinical signs of the dog were well-controlled without deterioration.

Conclusions

This case report describes long-term medical management without adrenalectomy of PCC complicated with atypical Cushing’s syndrome and DM.

Capillary hemoglobin electrophoresis of healthy and anemic dogs: Quantification, validation, and reference intervals of hemoglobin fractions

Despite the advances in canine medicine and the rapid gaining of attention of canine models in biomedical field and particularly in hemoglobin genes research, the studies on canine hemoglobin composition are sparse with ambiguous findings. Our aim was: i) to investigate the electrophoretic pattern of canine hemoglobin and the possible effects of age, sex, and anemia using a capillary electrophoresis assay, and ii) to validate this assay and calculate reference intervals (RIs) for canine hemoglobin fractions. Blood samples were collected from 53 healthy and 42 dogs with regenerative and non-regenerative anemias. The Sebia Capillarys 2 flex-piercing was used for hemoglobin analysis and it was validated using canine blood samples. R statistical language was employed for the statistical analyses. A major hemoglobin fraction (named HbA0) and a minor one (named HbA2) were identified in 100% and 47.4% of samples, respectively. The within-run and between-run CV was 0.1% for HbA0, and 9.1% and 11.2% for HbA2, respectively. The extremely narrow range of HbA0 and HbA2 values hampered a linearity study using canine blood samples. The RIs for HbA0 and HbA2 were 98.9-100% and 0-1.1%, respectively. HbA0 and HbA2 values were not significantly correlated with age (P = 0.866) or reticulocyte count (P = 0.731). No differences were observed in the median HbA0 and HbA2 between the two sexes (P = 0.887), and healthy and anemic dogs (P = 0.805). In conclusion, the capillary electrophoresis revealed a major hemoglobin fraction and an inconsistently present minor fraction. No effect of age, sex, anemia, or regenerative status of anemia was detected. The assay used was validated and RIs were generated, so as to be suitable for use in future investigations.

Evaluation of a human glycated hemoglobin test in canine diabetes mellitus

Glycated hemoglobin A1c (HbA1c) is widely used for monitoring and diagnosing human diabetes mellitus, but is rarely used in veterinary clinics. The goal of our study was to validate the commercial HbA1c testing system SD A1cCare analyzer (Bionote, Gyeoggi-do, South Korea) for use in dogs. Dogs were recruited with owner's consent. Diabetic status was determined based on clinical signs, fasting hyperglycemia, and glycosuria. Intra-assay precision and linearity were evaluated with EDTA, heparin, or citrate as anticoagulants, and had excellent precision with mean coefficients of variation (CVs) of 2.47%, 2.26%, and 1.92%, respectively. Diluted anticoagulated blood samples showed excellent linear relationships with R2 of 0.991, 0.996, and 0.994, respectively. Inter-assay precision revealed that the mean CV of the normal control was 2.18% and that of the high control was 2.01% (30 repeats). Observed total error of a normal control was 7.81%, and 6.12% for the high control. HbA1c level measured before and after removal of plasma and replacement by saline showed minimal interference by lipid contents ( p = 0.929). The HbA1c concentrations of diabetic dogs were significantly higher than those of non-diabetic dogs ( p < 0.001). HbA1c value >6.2% indicated canine diabetes through a classification and regression tree model. In most cases, fructosamine and HbA1c were highly correlated ( r = 0.674, p < 0.001). The HbA1c testing system could be a valuable testing system to evaluate canine diabetes mellitus, providing an alternative in-house option for use by veterinary clinicians.