Comparison of measurements of canine plasma creatinine, glucose, proteins, urea, alanine aminotransferase, and alkaline phosphatase obtained with Spotchem SP 4430 and Vitros 250 analyzers

Detailed Structure and Pathophysiological Roles of the IgA-Albumin Complex in Multiple Myeloma

Immunoglobulin A (IgA)-albumin complexes may be associated with pathophysiology of multiple myeloma, although the etiology is not clear. Detailed structural analyses of these protein-protein complexes may contribute to our understanding of the pathophysiology of this disease. We analyzed the structure of the IgA-albumin complex using various electrophoresis, mass spectrometry, and in silico techniques. The data based on the electrophoresis and mass spectrometry showed that IgA in the sera of patients was dimeric, linked via the J chain. Only dimeric IgA can bind to albumin molecules leading to IgA-albumin complexes, although both monomeric and dimeric forms of IgA were present in the sera. Molecular interaction analyses in silico implied that dimeric IgA and albumin interacted not only via disulfide bond formation, but also via noncovalent bonds. Disulfide bonds were predicted between Cys34 of albumin and Cys311 of IgA, resulting in an oxidized form of albumin. Furthermore, complex formation prolongs the half-life of IgA molecules in the IgA-albumin complex, leading to excessive glycation of IgA molecules and affects the accumulation of IgA in serum. These findings may demonstrate why complications such as hyperviscosity syndrome occur more often in patients with IgA dimer producing multiple myeloma.

Electrolyte measurements differ between point-of-care and reference analysers in dogs with hypoadrenocorticism

INTRODUCTION

Dogs treated for hypoadrenocorticism are monitored through analysis of their blood electrolytes. This is routinely performed with point-of-care analysers and doses of medications are adjusted based on the results.

OBJECTIVES

To investigate the performance of two point-of-care analysers (IDEXX Catalyst Dx and IDEXX VetStat) against a reference laboratory method for the measurement of blood sodium, potassium and chloride concentrations, as well as sodium: potassium ratios, in dogs diagnosed with and treated for hypoadrenocorticism.

METHODS

Forty-eight dogs were enrolled into a prospective cross-sectional study. Paired blood samples were taken and tested on two point-of-care analysers and at a reference laboratory. Statistical analysis was then performed with Bland-Altman analysis and Passing-Bablok regression. The clinical effects of inaccurate electrolyte analysis were investigated.

RESULTS

In total, 329 samples were tested on the Catalyst analyser, while another 72 samples were tested on the VetStat. Passing-Bablok regression identified both proportional and constant bias for some analytes. There was poor agreement between sodium and chloride concentrations on both analysers. Both analysers tended to give higher results than the reference method for all analytes, except for potassium when measured on the VetStat.

CLINICAL SIGNIFICANCE

There are inherent differences between the electrolyte concentrations measured by these two point-of-care analysers and reference laboratory methods in dogs with hypoadrenocorticism.

Measurement of thyroxine and cortisol in canine and feline blood samples using two immunoassay analysers

OBJECTIVES

The AIA-360 (Tosoh Corporation) is an automated immunoassay analyser. The aims of this study were to estimate the precision of thyroxine and cortisol AIA-360 immunoassays in canine and feline samples and to compare the results produced with those obtained by a chemiluminescence analyser (Immulite® 1000, Siemens).

METHODS

Blood samples from 240 clinical cases (60 dogs and 60 cats for both thyroxine and cortisol) were analysed using both instruments.

RESULTS

Deming regression calculations showed excellent correlation (thyroxine, canine rs  = 0 · 94, feline rs  = 0 · 97; cortisol, canine rs  = 0 · 97, feline rs  = 0 · 97). Agreement between the two instruments was examined by Bland-Altman difference plots, which identified wide confidence intervals and outliers for thyroxine (canine n = 6, feline n = 4) and cortisol (canine n = 3, feline n = 4) results. Inter/intra-run precision of the AIA-360 was excellent for both cortisol and thyroxine (coefficients of variation <7%).

CLINICAL SIGNIFICANCE

The instrument showed excellent correlation for cortisol and thyroxine in canine and feline samples demonstrating that the AIA-360 can be used in clinical practice. The agreement studies suggest that the results from the AIA-360 cannot be used interchangeably with those generated by the Immulite 1000 and should be interpreted using reference intervals that have been established specific to the AIA-360.

Biochemical assessment of canine body cavity effusions using three bench-top analysers

OBJECTIVES

To assess the performance of three bench-top chemistry instruments for the analysis of canine effusions. Acceptable results were compared with those obtained by a reference chemistry analyser.

METHODS

Total protein, albumin, creatinine and bilirubin concentrations were measured in 74 effusions using the VetScanVS2, VetTest8008 and SpotchemEZ analysers. Cholesterol and triglyceride concentrations were also measured by the VetTest and Spotchem. Results were analysed using Westgard's error analysis, Spearman's correlation, Bland-Altman plots and Deming regression. Results were considered acceptable when observed total error (TE(obs) ) was less than allowable total error (TE(A) ).

RESULTS

VetScan error analysis revealed acceptable results for total protein (TE(obs) =1.11, TE(A) =4.7) and creatinine (TE(obs) =42.2, TE(A) =78.1). Correlation was fair for protein (r(s) =0.66) and creatinine (r(s) =0.76), but poor and not significant for bilirubin (r(s) =0.01, P=0.08), precluding error analysis. VetTest error analysis was acceptable for creatinine only (TE(obs) =5.55, TE(A) =25.5). Correlation was good (r(s) =0.81). The difference plot revealed a bias (95% confidence interval) of -1.5 (-37 to 40) and four outliers. The Spotchem did not generate a precise arithmetic value in most (56.9 to 73.6%) samples, precluding further analysis.

CLINICAL SIGNIFICANCE

Acceptable results were obtained for total protein (VetScan) and creatinine [Vetscan, Vettest (with good correlation)]. The Spotchem is of limited value in canine effusion analysis.

Comparison of measurements of 18 analytes in canine and feline blood samples using the in-practice Falcor 350 and the reference KoneLab 30i analysers

OBJECTIVES

Falcor 350 (A. Menarini Diagnostics) is a wet-reagent biochemistry analyser that is available for in-house use. The aim of this study was to compare the results produced by this analyser with those obtained by a wet-reagent analyser (KoneLab 30i; Thermo Clinical Labsystems) that served as the reference instrument.

METHODS

Blood samples from 120 clinical cases (60 dogs and 60 cats) were analysed for 18 analytes (urea, creatinine, total proteins, albumin, creatine kinase, aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, total bilirubin, amylase, lipase, glucose, triacylglycerol, cholesterol, total calcium, phosphate, sodium and potassium) using both the reference and Falcor instruments.

RESULTS

Good to excellent correlations (r(s) value) (canine/feline) were identified for urea (0.87/0.86), creatinine (0.96/0.99), total proteins (0.91/0.95), albumin (0.96/0.93), creatine kinase (0.98/0.99), aspartate aminotransferase (0.95/0.98), alanine aminotransferase (0.99/0.99), alkaline phosphatase (0.99/0.98), total bilirubin in dogs (0.88), amylase (0.99/0.87), lipase in dogs (0.88), glucose (0.97/0.98), triacylglycerol (0.93/0.97), cholesterol (0.99/0.99), total calcium (0.88/0.89), phosphate (0.94/0.97) and potassium (0.96/0.97). The correlations for sodium (0.41/0.61), total bilirubin in cats (0.78) and lipase in cats (0.25) were considered unacceptable.

CLINICAL SIGNIFICANCE

For 13 of the 18 analytes (creatinine, total proteins, albumin, creatine kinase, aspartate aminotransferase, alanine aminotransferase, amylase, glucose, cholesterol, triacylglycerol, phosphate, potassium and urea) in both canine and feline samples, the two instruments produce values that are closely related to each other (excellent correlation) and are sufficiently similar to allow them to be used interchangeably without the need for additional correction factor computations (good agreement). Because of differences in the methodologies, the Falcor results for alkaline phosphatase, total calcium, sodium, lipase and total bilirubin cannot be used interchangeably with those generated by the KoneLab and should be interpreted using reference intervals established from the Falcor analyser.

Comparison of measurements of canine plasma glucose, creatinine, urea, total proteins, alanine aminotransferase, and alkaline phosphatase obtained with the APOLOWAKO and Vitros 250 analyzers

The APOLOWAKO is an entirely automatic benchtop biochemistry analyzer that uses stabilized liquid reagents. It was tested for canine blood and plasma glucose, creatinine, urea, total proteins, alanine aminotransferase, and alkaline phosphatase. The APOLOWAKO gave very similar results for whole blood and the corresponding plasma (n=32). Within-laboratory imprecision was below 2.2% and 5.8% for substrates and enzymes, respectively. Comparison of results with whole blood by APOLOWAKO and with the corresponding plasma by Vitros 250 (n=139) showed very good correlations. Passing-Bablok's regression slopes ranged from 0.83 to 1.12 and intercepts were close to zero, except for ALP where the results obtained by APOLOWAKO were approximately 1.5 times higher than by Vitros. The APOLOWAKO system can be a reliable instrument in veterinary practices where larger systems are not available but it should be further validated and reference intervals should be determined.