The use of an early postoperative CRH test to assess adrenal function after transsphenoidal surgery for pituitary adenomas

Abstract

Transsphenoidal surgery (TS) is the treatment of choice for many pituitary tumors. Because TS may cause pituitary insufficiency in some of these patients, early postoperative assessment of pituitary function is essential for appropriate endocrine management. The aim of our study was to evaluate the clinical relevance of the CRH-stimulation test in assessing postoperative pituitary-adrenal function. We performed a retrospective analysis of 144 patients treated by TS between January 1990 and November 2009, in whom a CRH-test and a second stimulation test was performed to assess adrenal function during follow-up. Patients with Cushing's disease were excluded. Hydrocortisone substitution was started if peak cortisol levels were <550 nmol/L. The cortisol response was insufficient in 42(29%) and sufficient in 102 patients at the postoperative CRH-test. Thirteen of 42(30%) demonstrated a normal cortisol response during a second cortisol stimulation test. In 75 of the 102 patients with a sufficient response to CRH repeat testing revealed an insufficient cortisol response in 14 patients (14%). All but one had concomitant pituitary hormone deficits. There were no cases of adrenal crises during follow-up. Additional pituitary insufficiency was significantly more present (P < 0.001) in the group of patients with an abnormal response to CRH directly after surgery. In this study a substitution strategy of hydrocortisone guided by the postoperative cortisol response to CRH appeared safe and did not result in any case of adrenal crises. However, the early postoperative CRH-test does not reliably predict adrenal function after TS for pituitary adenomas in all patients and retesting is mandatory.

Fig. 1

Flow-chart of patient selection and follow-up. AI = adrenal insufficiency. *pre-existent panhypopituitarism before or immediately after surgery (n = 12), pre-existent isolated severe adrenal insufficiency before surgery (n = 4) or very low basal serum cortisol concentrations (mean 10 nmol/L) during follow-up after surgery (n = 4). **basal serum cortisol levels > 550 nmol/L (n=12), normal urine cortisol levels (n=3), short follow-up between repeated surgery or additional radiotherapy (n = 2), and follow-up <1 year (n = 2) or unspecified reasons (n = 7), basal serum cortisol <110 nmol/L (n = 1)

Fig. 2

Proposed algorithm for the postoperative follow-up of adrenal function in non ACTH dependent pituitary disease (HC hydrocortisone)