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

J Small Anim Pract. 2014 Mar;55(3):153-9. doi: 10.1111/jsap.12181. Epub 2014 Jan 20.

Abstract

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.

MeSH terms

  • Animals
  • Autoanalysis / instrumentation
  • Autoanalysis / veterinary
  • Cats / blood
  • Dogs / blood
  • Hydrocortisone / blood*
  • Immunoassay / instrumentation
  • Immunoassay / veterinary*
  • Luminescent Measurements / veterinary
  • Thyroxine / blood*

Substances

  • Thyroxine
  • Hydrocortisone