Affiliation:
1. Department of Investigative Medicine, Imperial College London, Hammersmith Hospital, London, UK
2. Department of Neurosurgery, Imperial College Healthcare NHS Trust, Charing Cross Hospital, London, UK
Abstract
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.
Publisher
Oxford University Press (OUP)
Subject
Biochemistry (medical),Clinical Biochemistry
Cited by
36 articles.
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