ABSTRACT
Timed cortisol responses to insulin-hypoglycemia (IH) and arginine-vasopressin (AVP) were compared in 16 patients with pituitary tumors and six healthy controls. Serum cortisol was estimated by a specific and sensitive radioimmunoassay as per the WHO protocol. The basal cortisol (AM) was normal (> 290 nmol/l) in 9 patients and low in seven. With IH peak cortisol response was normal (> 550 nmol/l) in 10 patients, 8 of whom had normal and 2 had low basal (AM) cortisol. In contrast AVP evoked normal cortisol responses in only 5 of these patients, all of whom had normal basal (AM) cortisol and none had low basal (AM) cortisol. The data indicate lower sensitivity for AVP stimulation test (50%) and favour IH as the standard cortisol stimulation test in patients with pituitary tumors awaiting surgery.
Subject(s)
Adolescent , Adult , Arginine Vasopressin/diagnosis , Female , Humans , Hydrocortisone/blood , Hypoglycemia/chemically induced , Hypothalamo-Hypophyseal System/physiology , Insulin/diagnosis , Male , Pituitary Neoplasms/physiopathology , Pituitary-Adrenal Function Tests , Pituitary-Adrenal System/physiologyABSTRACT
Assessment of the hypothalamo-pituitary-adrenal axis is essential to determine the strength of the adrenocorticotrophic hormone (ACTH) reserve in relation to clinical and subclinical hypocortisolaemia. The insulin tolerance test has been established as the gold standard; however, the time and the potential hazards involved have led to a search for more viable alternatives. Numerous tests have evolved, which include the 8 a.m. fasting plasma cortisol, standard short synacthen test, low dose (1 microgram) synacthen test, metyrapone provocation and glucagon stimulation test. The low-dose (1 microgram) synacthen stimulation test has emerged as a potential alternative but further well designed trials are required to establish this.
Subject(s)
Adrenal Cortex Function Tests , Humans , Hypothalamo-Hypophyseal System/physiopathology , Insulin/diagnosis , Pituitary-Adrenal System/physiopathologyABSTRACT
This study evaluates the relative merits of the five most commonly used criteria for interpreting the results of the insulin test for completeness of vagotomy. One hundred and eighty tests were performed in normal controls and in patients with duodenal ulcer studied both preoperatively and after truncal vagotomy and drainage. It was found that Hollander's original criteria especially the response in the first post insulin hour was more useful than other criteria. Further use of multiple criteria instead of one alone, has a greater predictive value than mere statement of a positive or negative Hollander response.