Immunoreactive Cortisol Measurement in Canine Urine and its Validity in Hyperadrenocorticism Diagnosis

Abstract

Kolevska J., M. Svoboda: Immunoreactive Cortisol Measurement in Canine Urine and its Validity in Hyperadrenocorticism Diagnosis. Acta Vet. Brno 2000, 69: 217–223. The aim of this study was to compare two methods of immunoreactive cortisol determination in urine and an assessment of the validity of urine cortisol/creatinine ratio (UCCR) in dogs. The UCCR was measured in three groups of dogs: (1) healthy dogs, (2) dogs with hyperadrenocorticism and (3) dogs suffering from other diseases presented with polyuria and polydipsia (PU/PD). All cortisol measurements in urine were performed using two methods: (1) fluorescence polarisation immunoassay (FPIA) with urine extraction and (2) radioimmunoassay (RIA) without urine extraction. Paired results of 30 cortisol measurements and 30 UCCR were compared using the Wilcoxon test. It was proved that the differences between the two methods (i.e., FPIA with urine extraction and RIA without urine extraction) were highly statistically significant (p < 0.01). While in the cortisol measurement using the FPIA with urine extraction the median of the UCCR amounted to 18.53 × 10-6, in the RIA without urine extraction it was 37.83 × 10-6. Values of the UCCR in individual canine groups were also compared with each other. The UCCR in dogs with hyperadrenocorticism was higher (p < 0.01) than in healthy dogs or dogs presented with the PU/PD signs. There were also found significant differences (p < 0.05) between the UCCR in healthy dogs and dogs presented with PU/PD signs. Both methods of immunoreactive cortisol determination in urine can be used for clinical diagnosis of hyperadrenocorticism, however, the above mentioned differences should be considered. Hyperadrenocorticism, cortisol, creatinine, RIA, FPIA, urine extraction