title: Day 5 morning serum cortisol predicts hypothalamic-pituitary-adrenal function after transsphenoidal surgery for pituitary tumors.
abstract: BACKGROUND
  Adrenal insufficiency is a complication of transsphenoidal surgery (TSS) for pituitary adenoma, and correct identification of patients requiring glucocorticoid replacement is important. Controversy exists over which early postoperative 9 AM cortisol concentration reliably predicts hypothalamic-pituitary-adrenal (HPA) axis reserve, as defined by the insulin tolerance test (ITT).
  
  
  METHODS
  Data were reviewed for 36 patients undergoing TSS followed by day 5 postoperative 9 AM cortisol measurement and ITT 6 weeks postsurgery. All patients received postoperative glucocorticoid replacement, which was discontinued if the 9 AM serum cortisol was >300 nmol/L.
  
  
  RESULTS
  Of 23 patients who failed the ITT (peak cortisol <500 nmol/L), 20 also had a day 5, 9 AM serum cortisol <300 nmol/L. Nine of 13 patients who passed the ITT had a day 5, 9 AM cortisol >300 nmol/L. The cutoff cortisol concentration of 300 nmol/L had 86.9% (66.4%-97.2%) diagnostic sensitivity, 69.2% (38.6%-90.9%) diagnostic specificity, and 83.3% (61.8%-94.5%) positive predictive value (PPV) for detecting secondary adrenal insufficiency. Increasing the cutoff to 392 nmol/L resulted in 100% (85.2%-100%) sensitivity, 46.1% (19.2%-74.9%) specificity, and 76.6% (57.3%-89.4%) PPV. Decreasing the cutoff to 111 nmol/L resulted in 100% (75.3%-100%) specificity and 100% (67.9%-100%) PPV, although sensitivity was 47.8% (26.8%-69.4%).
  
  
  CONCLUSIONS
  A day 5 post-TSS 9 AM serum cortisol <111 nmol/L reliably detects secondary adrenal insufficiency, and concentrations >392 nmol/L support intact HPA function. Because concentrations of 111-392 nmol/L are poorly predictive of HPA function, glucocorticoid replacement should continue in such cases until definitive testing is performed using an ITT.
authors.affiliation: Department of Investigative Medicine, Imperial College London, Hammersmith Hospital, London, UK.
authors.forename: Channa N
authors.initials: CN
authors.lastname: Jayasena
authors.forename: Kunal A
authors.initials: KA
authors.lastname: Gadhvi
authors.forename: Bhavini
authors.initials: B
authors.lastname: Gohel
authors.forename: Niamh M
authors.initials: NM
authors.lastname: Martin
authors.forename: Nigel
authors.initials: N
authors.lastname: Mendoza
authors.forename: Karim
authors.initials: K
authors.lastname: Meeran
authors.forename: Waljit S
authors.initials: WS
authors.lastname: Dhillo
mesh_terms: D000309:Adrenal Insufficiency / Q000097:blood* / Q000188:drug therapy / Q000503:physiopathology; D000328:Adult; D000368:Aged; D005260:Female; D005938:Glucocorticoids / Q000627:therapeutic use; D006801:Humans; D006854:Hydrocortisone / Q000097:blood*; D007030:Hypothalamo-Hypophyseal System / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D010911:Pituitary Neoplasms / Q000097:blood* / Q000503:physiopathology / Q000601:surgery; D010913:Pituitary-Adrenal System / Q000502:physiology*; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D055815:Young Adult
chemical_list: D005938:Glucocorticoids; D006854:Hydrocortisone