Low- and Standard-Dose Corticotropin and Insulin Hypoglycemia Testing in the Assessment of Hypothalamic-Pituitary-Adrenal Function after Pituitary Surgery

C. Hamish Courtney, Andrew S. McAllister, Patrick M. Bell, David R. McCance, Hilary Leslie, Brian Sheridan, A. Brew Atkinson
2004 Journal of Clinical Endocrinology and Metabolism  
The optimal means of assessing the integrity of the hypothalamic-pituitary-adrenal (HPA) axis after pituitary surgery remains controversial. We compared low-dose (1 g iv) and standard-dose (250 g im) corticotropin tests performed 1 and 4 -6 wk after pituitary surgery with an insulin hypoglycemia test performed at 4 -6 wk. Forty-one patients (21 male and 20 female; median age, 52 yr; range, 23-73 yr) who had undergone pituitary surgery were studied (Cushing's disease excluded). Twenty-two of the
more » ... 41 patients had normal cortisol responses to all tests both at 1 and 4 -6 wk after surgery. Eight patients had subnormal cortisol responses to all tests. Of the 11 patients with discrepant results, seven had subnormal responses only after the low-dose corticotropin test; the remaining four patients had borderline responses to one or more tests. At 4 -6 wk after surgery, subjects with a 30-min serum cortisol after standarddose corticotropin of less than 350 nmol/liter (12.7 g/dl) consistently had a subnormal response to hypoglycemia, and those with a serum cortisol greater than 650 nmol/liter (23.6 g/dl) had a normal response to hypoglycemia. Definitive testing of the HPA axis using the standard-dose corticotropin test can be carried out provided it is performed at least 4 wk after pituitary surgery. A 30-min cortisol level greater than 650 nmol/liter (23.6 g/dl) indicates adequacy of the HPA axis, and a level of less than 350 nmol/liter (12.7 g/dl) indicates ACTH deficiency. No further testing is then required. An intermediate level of 350 -650 nmol/liter (12.7-23.6 g/dl) warrants further assessment using the insulin hypoglycemia test
doi:10.1210/jc.2003-031577 pmid:15070935 fatcat:ozmnwuzzsze2lc7si6shxuv66q