The serum concentrations of
cortisol,
17alpha-hydroxypregnenolone, 17alpha-hydroxyprogesterone,
21-deoxycortisol and
11-deoxycortisol were measured in 19 healthy dogs, 15 dogs with pituitary-dependent
hypercortisolism (pdh) and eight dogs with other diseases before and one hour after an injection of synthetic
adrenocorticotrophic hormone (
acth). At both times the dogs with pdh had significantly higher concentrations of
cortisol,
17alpha-hydroxypregnenolone, 17alpha-hydroxyprogesterone and
21-deoxycortisol than the healthy dogs. Basal
11-deoxycortisol concentrations were also significantly higher in dogs with pdh compared with healthy dogs. When compared with the dogs with other diseases, the dogs with pdh had significantly higher basal and post-
acth cortisol and basal
21-deoxycortisol, and significantly lower post-
acth 11-deoxycortisol concentrations. The dogs with other diseases had significantly higher post-
acth cortisol, 17alpha-hydroxyprogesterone and
11-deoxycortisol concentrations than the healthy dogs. In general, the post-
acth concentrations of
17alpha-hydroxypregnenolone, 17alpha-hydroxyprogesterone,
11-deoxycortisol and
21-deoxycortisol were more variable than the post-
acth concentrations of
cortisol, resulting in large overlaps of the concentrations of these
hormones between the three groups. A two-graph receiver operating characteristic (ROC) analysis was used to maximise the sensitivity and specificity of each
hormone for diagnosing
hypercortisolism; it showed that the post-
acth concentration of
cortisol had the highest sensitivity and specificity. The overlaps between the healthy dogs, the dogs with pdh and the dogs with other diseases suggested that the individual precursor
hormones would not be useful as a screening test for
hypercortisolism.