Determination of Multi‐Steroid Profiles of Cats With Hyperaldosteronism or Other Diseases: A Retrospective Study

ABSTRACT Background Multi‐steroid profiles are proven to help with the diagnostic approach to adrenal disorders in humans. Objectives Compare liquid chromatography tandem mass spectrometry (LC–MS/MS) and radioimmunoassay (RIA) measurement of aldosterone in feline blood samples. Evaluate multi‐steroid profiles in cats with hyperaldosteronism. Animals Client‐owned cats with low/normal aldosterone by RIA (low aldo, n = 15), high aldosterone by RIA (high aldo, n = 6) and overt primary hyperaldosteronism (PHA, n = 6). Methods Exploratory retrospective case–control study. Feline blood multi‐steroid profiles were analyzed with LC–MS/MS and compared with results from a commercially available RIA in widespread clinical use. Results Aldosterone measurement by LC–MS/MS and RIA was strongly correlated (r = 0.93, p < 0.001) but showed a bias of 56 (95% CI: 104–7) pmol/L, with RIA giving higher values. Creatinine concentration was not significantly associated with the discrepancy between methods (p = 0.95). Cats with PHA had significantly lower serum concentrations of cortisol and glucocorticoid precursors (17‐hydroxyprogesterone, 11‐deoxycortisol), testosterone, and significantly higher dihydrotestosterone and 5α‐dihydroprogesterone concentrations than the low aldo group. Pregnenolone concentrations were significantly lower in the PHA group than in the high aldo group. Conclusion and Clinical Importance Quantification of aldosterone by either LC–MS/MS or RIA is adequate for PHA diagnosis in the clinical setting, with appropriate method‐specific reference intervals. Cats with PHA had different concentrations of some steroids compared with the control groups, but overt steroid excess (other than aldosterone) was not observed.