Prospective evaluation of a week one overnight metyrapone test with subsequent dynamic assessments of hypothalamic-pituitary-adrenal axis function after pituitary surgery.
OBJECTIVE
To determine whether an overnight metyrapone test (OMT) within the first week postpituitary surgery can definitively assess the hypothalamic-pituitary-adrenal (HPA) axis, compared with subsequent dynamic tests and glucocorticoid requirement at 6 months.


METHODS
Prospective study measuring morning cortisol levels on days 3 and 4 post-operatively, OMT day 5-7 and week 6, week 6 250 μg short Synacthen test (SST) and week 7 insulin tolerance test (ITT).


METHODS
Forty participants who underwent pituitary surgery at a single centre (Cushing's disease excluded) were followed for at least 6 months. 46% had pre-operative adrenal insufficiency.


METHODS
week 1 OMT compared to glucocorticoid requirement at 6 months.


RESULTS
the performance of ITT as a "definitive" test and all tests compared to glucocorticoid requirement at 6 months.


RESULTS
Week 1 OMT showed concordance with ITT at week 7 of 78% and glucocorticoid requirement at 6 months of 81% respectively which was not significantly different from post-operative morning cortisol levels; 37% of participants with an abnormal OMT on day 6 had a normal OMT at week 6. All HPA axis tests showed similar concordance with glucocorticoid requirement at 6 months of 80%-85%.


CONCLUSIONS
Overnight metyrapone test within the first week after pituitary surgery was no better than an early morning cortisol level at predicting glucocorticoid requirement at 6 months. OMT at week 6 demonstrated recovery of HPA axis in a substantial proportion of participants who failed earlier assessments; thus, definitive testing should be delayed until 6 weeks post-operatively.
Department of Diabetes and Endocrinology, Princess Alexandra Hospital, Brisbane, Queensland, Australia.|Faculty of Medicine, University of Queensland, Brisbane, Queensland, Australia.
Katherine
K
English
Department of Diabetes and Endocrinology, Princess Alexandra Hospital, Brisbane, Queensland, Australia.|Faculty of Medicine, University of Queensland, Brisbane, Queensland, Australia.
Warrick J
http://orcid.org/0000-0001-5078-4980
WJ
Inder
Department of Diabetes and Endocrinology, Princess Alexandra Hospital, Brisbane, Queensland, Australia.
Zara
Z
Weedon
Faculty of Medicine, University of Queensland, Brisbane, Queensland, Australia.|Department of Chemical Pathology, Princess Alexandra Hospital, Brisbane, Queensland, Australia.
Goce
G
Dimeski
Department of Diabetes and Endocrinology, Princess Alexandra Hospital, Brisbane, Queensland, Australia.
Jane
J
Sorbello
Department of Diabetes and Endocrinology, Princess Alexandra Hospital, Brisbane, Queensland, Australia.|Faculty of Medicine, University of Queensland, Brisbane, Queensland, Australia.
Anthony W
AW
Russell
Faculty of Medicine, University of Queensland, Brisbane, Queensland, Australia.|Department of Endocrinology and Diabetes, Royal Brisbane and Women's Hospital, Brisbane, Queensland, Australia.|Institute of Health and Biomedical Innovation, Faculty of Health, Queensland University of Technology, Brisbane, Queensland, Australia.
Emma L
EL
Duncan
Department of Diabetes and Endocrinology, Princess Alexandra Hospital, Brisbane, Queensland, Australia.
Ross
R
Cuneo
D000309:Adrenal Insufficiency / Q000601:surgery; D000328:Adult; D005260:Female; D005938:Glucocorticoids / Q000627:therapeutic use; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D007030:Hypothalamo-Hypophyseal System / Q000502:physiology*; D008297:Male; D008797:Metyrapone / Q000008:administration & dosage / Q000494:pharmacology*; D008875:Middle Aged; D010902:Pituitary Gland / Q000601:surgery*; D010913:Pituitary-Adrenal System / Q000502:physiology*; D011184:Postoperative Period; D011237:Predictive Value of Tests; D011446:Prospective Studies; D020127:Recovery of Function / Q000502:physiology*; D013252:Steroid 11-beta-Hydroxylase / Q000037:antagonists & inhibitors; D013997:Time Factors
D005938:Glucocorticoids; D013252:Steroid 11-beta-Hydroxylase; D006854:Hydrocortisone; D008797:Metyrapone
cortisol; glucocorticoid replacement; metyrapone; pituitary surgery