Concentrations of Noncortisol Adrenal Steroids in Response to ACTH in Dogs with Adrenal‐Dependent Hyperadrenocorticism, Pituitary‐Dependent Hyperadrenocorticism, and Nonadrenal Illness

Abstract

Increases of adrenal hormone concentrations other than cortisol have been reported in dogs with hyperadrenocorticism (HAC). Measuring noncortisol adrenal hormone concentrations will help identify HAC in dogs. The objective was to determine plasma cortisol, androstenedione, estradiol, progesterone, testosterone, and 17-hydroxyprogesterone concentrations during ACTH stimulation testing of dogs with clinical signs of HAC to ascertain their utility in diagnosis of the disease. Ninety dogs with clinical findings consistent with HAC had ACTH stimulation tests performed. Results from 29 dogs were excluded from analysis because diagnoses were inconclusive for a variety of reasons. Results from 32 dogs with HAC and 29 dogs with disease other than HAC were analyzed. Prospective observational study. Concentrations of adrenocortical hormones were determined before and 1 hour after injecting 5 μg/kg ACTH IM. Diagnoses were determined by response to therapy, histopathology or both. Post-ACTH cortisol (P < .001), progesterone (P = .001), and 17-hydroxyprogesterone (P < .001) concentrations were associated with a diagnosis of HAC. Sensitivity and specificity, respectively, for diagnosing HAC for post-ACTH cortisol were 84 and 59%, progesterone 88 and 55%, and 17-hydroxyprogesterone 91 and 59%, and for post-ACTH cortisol, progesterone and 17-hydroxyprogesterone combined were 88 and 55%. Of 5 dogs with HAC and normal post-ACTH cortisol concentrations, 5 had increased progesterone and 4 had increased 17-hydroxyprogesterone. Serum progesterone and 17-hydroxyprogesterone concentrations were useful to diagnose HAC in this study, but were not more sensitive or specific than cortisol concentration.