Comparison of the Acth and Cortisol Responses to Provocative Testing With Glucagon and Insulin Hypoglycaemia in Normal Subjects

Abstract

The glucagon stimulation test (GST) is often used to assess pituitary ACTH reserve, particularly when other tests are contra-indicated. In a preliminary investigation, in patients with pituitary disease, we failed to demonstrate the ACTH dependence of the cortisol response. We have therefore compared the ACTH, cortisol and glucose responses to glucagon (1 mg s.c.), insulin (0.2 U/kg i.v., ITT) and placebo in six healthy male volunteers, sampling every 10 min for 6 h. During the GST, mean +/- SD serum cortisol rose from 256 +/- 80 nmol/l to a peak of 481 +/- 164 nmol/l (range 289-717 nmol/l, P less than 0.01) in comparison with 280 +/- 81 nmol/l to 602 +/- 110 nmol/l (range 493-742 nmol/l) during the ITT (P less than 0.002). The mean peak cortisol levels achieved in the two tests did not differ significantly. In the GST, plasma ACTH rose from a mean basal value of 10.9 +/- 16.6 ng/l to a mean peak level of 123 +/- 76 ng/l (P less than 0.02) (ACTH ng/l x 0.225 = pmol/l). The corresponding values in the ITT were 7.1 +/- 16.2 ng/l and 263 +/- 91 ng/l (P less than 0.001). The mean peak ACTH level was significantly greater during the ITT (P less than 0.05). Thus the cortisol response was ACTH dependent in both the GST and the ITT in normal subjects. Furthermore, the ACTH response was of sufficient duration to be detected by the usual procedure of sampling every 30 min.(ABSTRACT TRUNCATED AT 250 WORDS)

Glucagon Stimulation Testing in Adult Growth Hormone Deficiency— A 2014 Update

“…Additionally, no correlation between BMI and age to peak GH responses were observed, peak GH responses occurred mainly between 120 and 180 minutes consistent with previous studies, 27,30 and that, overall, the GST was a well tolerated test. Nevertheless, these 21,22,28 and previous studies 20,23,24,31 did not specifically evaluate patients with glucose intolerance and frank diabetes and, for this reason, the characteristic of the GST and its reliability in testing for GHD in this population remains unclear.…”

Low prevalence of hypopituitarism after subarachnoid haemorrhage using confirmatory testing and with BMI-specific GH cut-off levels

“…The response to GHRH/arginine was stratified by BMI (cut-off for severe GHD: GH!11.5 mg/l for BMI !25 kg/m 2 , !8 mg/l for BMI 25-30 kg/m 2 and !4.2 mg/l for BMI O30 kg/m 2 ) (17). Cortisol insufficiency was defined as a peak cortisol !500 nmol/l to both glucagon and synacthen testing (18). Gonadotrophin deficiency in males was defined as an early morning testosterone of !8.5 nmol/l (lower limit of normal range for assay) on two occasions with gonadotrophins within the normal range, and confirmation testing at 12 months also required a free testosterone concentration below the normal range in addition to the above.…”

The Role of Corticosterone in the Metabolic Recovery after Intrasplenic Adrenal Autotransplantation in Rats

“…High glucagon concentrations may also contribute to the marked increase in plasma ACTH levels found in adrenalectomized and autotransplanted rats (Table 1), since previous studies demonstrated that administration of glucagon evokes a considerably rise in the blood levels of ACTH [24,25]. It has also been reported that systemic or intracerebroventricular administration of glucagon raises plasma concentration of corticosterone in rats [26] and cortisol in humans [27,28]. Thus, it may well be that increased glucagon levels contribute to the partial recovery of plasma corticosterone observed in autotransplanted animals (Fig.…”