Biochemical characterization of pituitary-dependent hyperadrenocorticism in the dog.
The biochemical characterization of 22 cases of pituitary-dependent hyperadrenocorticism in the dog, is reported. The principal characteristics of the disease include excessive and non-rhythmic production of cortisol, decreased sensitivity of the hypothalamic-pituitary system to the suppressive effects of dexamethasone, decreased responsiveness of the pituitary-adrenocortical system to the stimulus of insulin-induced hypoglycaemia and increased responsiveness of the system to stimulation with lysine-vasopressin. From these observations it is concluded that pituitary-dependent hyperadrenocorticism in the dog is a valid model for study of the pathogenesis of the disease in man. For the diagnosis of hyperadrenocorticism itself, the measurement of the concentration of corticosteroids in a single sample of plasma obtained 8 h after intravenous injection of 0.01 mg dexamethasone/kg was sufficient. The level of 11-hydroxycorticosteroids was less than 140 nmol/1 plasma in normal dogs, whereas higher values were found in dogs with hyperadrenocorticism. For purposes of differential diagnosis, measurement of the level of corticosteroids in the plasma both before and 4 h after intravenous injection of 0.05 mg dexamethasone/kg is adequage: suppression is obtained only in cases of pituitary-dependent hyperadrenocorticism.
D015062:11-Hydroxycorticosteroids / Q000097:blood; D000324:Adrenocorticotropic Hormone; D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D003480:Cushing Syndrome / Q000175:diagnosis / Q000378:metabolism / Q000662:veterinary*; D003907:Dexamethasone; D004283:Dog Diseases / Q000175:diagnosis / Q000378:metabolism*; D004285:Dogs; D005260:Female; D006854:Hydrocortisone / Q000097:blood; D007328:Insulin; D008236:Lypressin; D008297:Male
D015062:11-Hydroxycorticosteroids; D001786:Blood Glucose; D007328:Insulin; D008236:Lypressin; D003907:Dexamethasone; D000324:Adrenocorticotropic Hormone; D006854:Hydrocortisone