Should post hypophysectomy patients be discharged on steroids? The use of 0900h-cortisol measurements as a screening test for pituitary-adrenal dysfunction
JN Walker, E Nickerson, SG Gardner, B Shine, HE Turner & JAH Wass
A Short Synacthen Test (SST) cannot be used to assess the pituitary-adrenal axis immediately post transphenoidal adenectomy (TSA). A 9am cortisol must be used to achieve a balance between avoiding hypoadrenalism and over treating with replacement steroids. In this study we have determined the cut-off levels at which an averaged cortisol is most accurate and at which patients can be safely discharged with/without regular steroids or an emergency pack.62 patients (M:F 34:28) with a median age 52 yrs (16-76) who had undergone TSA for conditions other than Cushing's disease (40 NFA, 16 Acromegaly, 3 Prolactinoma, 3 Other) were investigated. 0900h serum cortisol was measured on day three and day four post-surgery and a 250mcg SST performed at six weeks. Normality was defined as a 30 minute post-synacthen cortisol >550nmol/l.The averaged cortisol was a valid test for separating hypoadrenal and euadrenal groups (area under ROC curve 0.86 95% CI 0.74-0.93). 100% sensitivity required an averaged cortisol greater than or equal to 484nmol/l with a specificity of 40% (95% CI 24-57). Highest accuracy (minimal false negative and false positive results) occurred at 344 nmol\l at which the specificity was 77% (95% CI 55-92), sensitivity 84% (95% CI 69-94) and the SST >400nmol\l in all cases.Conclusion:Rounding figures for ease of use, a patient post TSA surgery with an averaged cortisol >500nmol\l can be safely discharged post surgery without steroid cover. Between 350 and 500nmol\l, 17% of patients will subsequently have an abnormal SST and this group should therefore be provided with an emergency steroid pack pending dynamic testing. Below 350nmol\l the patient should start on regular steroid replacement, although 30% will subsequently be shown to have a normal steroid axis. This study provides useful guidance for steroid management post hypophsectomy.