Abstract: Background- Liquid chromatography tandem mass spectrometry (LCMS) has been used to improve understanding of the underlying pathophysiology of human endocrinopathies. Multiple steroid excesses have been identified in cats with primary hyperaldosteronism (PHA). Hypothesis/Objectives- Cats with PHA will have alteration in other steroid hormones, in addition to aldosterone. Animals- Residual serum samples from cats with overt primary hyperaldosteronism (PHA, n=6), and control cats with high (n=6) or low/normal aldosterone (n=15) measured by radioimmunoassay. Methods- Case-control study. Blood samples were analysed for 20 steroids by LCMS. Kruskal Wallis one way ANOVA with Benjamini and Hochberg correction compared the three groups. Variables that were significant (p< 0.05) were followed up with post hoc pairwise Wilcoxon sign rank-sum tests. Results- 11 steroids were significantly different between groups (Table 1). Cats with PHA had lower glucocorticoid (including 17-hydroxyprogesterone, 11-deoxycortisol and cortisol), pregnenolone and testosterone and higher dihydrotestosterone and 5α-dihydroprogesterone concentrations than the low/normal aldosterone group. Pregnenolone concentrations were also lower in the PHA group than the high aldosterone group. The high aldosterone group had lower dihydrotestosterone and 5α-dihydroprogesterone and higher progesterone, mineralocorticoids (deoxycorticosterone, corticosterone), glucocorticorticoids (17-hydroxyprogesterone, 11-deoxycortisol) and testosterone than the low/normal aldosterone group. Conclusions and clinical importance- Cats with PHA had lower concentrations of glucocorticoids compared with cats with normal aldosterone, whilst cats with high aldosterone had higher glucocorticoids than the cats with normal aldosterone, suggesting differences in the underlying pathophysiology. Marked progesterone excess was not observed in the PHA group. Measurement of multiple steroids may be useful to investigate other endocrinopathies.
