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Updated: Aug 31, 2026
Fecal Glucocorticoid Analysis: Non-invasive Adrenal Monitoring in Equids
Published on: April 25, 2016
Poor specificity and recovery of urinary free cortisol as determined by the Bayer ADVIA Centaur extraction method
G Gray1, L Shakerdi, A M Wallace
1Department of Clinical Biochemistry, Macewen Building, Royal Infirmary, Glasgow G4 0SF, UK. gil10@supanet.com
Background:
Immunoassay methods for urinary free cortisol (UFC) lack specificity, and many procedures have not been fully evaluated for routine use. In the current study we evaluated the Bayer ADVIA Centaur extraction UFC immunoassay and compared results to those obtained by a specific gas chromatography-mass spectrometry (GC-MS) method.
Results:
The Bayer ADVIA Centaur cortisol assay lacked specificity. Cortisone, a steroid present in urine at concentrations similar to those of cortisol, demonstrated a cross-reactivity of 44%. In addition, the choice of matrix used to resuspend steroids after solvent extraction from urine affected recovery. Recovery was improved if the recommended urine reconstruction buffer was replaced by steroid-free serum.
Conclusion:
Irrespective of the sample matrix used, the Centaur method overestimates UFC, giving results up to twice those obtained by a specific GC-MS method.
