Predictability of hypoadrenalism occurrence and duration after adrenalectomy for ACTH-independent hypercortisolism

Objective: To evaluate if the parameters of hypothalamic\ue2\u80\u93pituitary\ue2\u80\u93adrenal (HPA) axis activity could predict the occurrence and duration of post-surgical hypocortisolism (PSH) in patients with Cushing\ue2\u80\u99s syndrome (CS) and with adrenal incidentaloma (AI). Methods: We studied 80 patients (54 females, age 53.3 \uc2\ub1 11 years), who underwent adrenalectomy for CS (17 patients) or for AI (53 patients). Before surgery, we measured adrenocorticotroph hormone (ACTH), urinary free cortisol (UFC) and serum cortisol after 1 mg dexamethasone suppression test (1 mg-DST) levels. After surgery, all patients were given a steroid replacement therapy, and PSH was searched after 2 months by a low-dose (1 \uc2\ub5g, iv) corticotropin stimulation test, that was repeated every 6 months in PSH patients for at least 4 years. Results: The PSH occurred in 82.4 and 46% of CS and AI patients, respectively. In the whole sample and in AI patients separately considered, the PSH was independently predicted by the preoperative cortisol levels after 1 mg-DST, however, with a low (< 70%) accuracy. In AI patients the PSH occurrence was not ruled out even by the cortisol levels after 1 mg-DST lower than 1.8 \uce\ubcg/dL (50 nmol/L). In the 50% of CS patients and in 31% of AI patients the PSH lasted more than 18 months and in 35.7% of CS patients it persisted for more than 36 months. In AI patients, the PSH duration was not predictable by any parameter. However, a PSH duration of at least 12 months was significantly predicted before adrenalectomy (sensitivity 91.7%, specificity 41.2%, positive predictive value 52.4%, negative predictive value 87.5%, p = 0.05) by the presence of at least 2 out of low ACTH levels, increased UFC levels and cortisol levels after 1 mg-DST \ue2\u89\ua5 3.0 \uc2\ub5g/dL (83 nmol/L). Conclusion: The PSH occurrence and its duration are hardly predictable before surgery. All patients undergoing unilateral adrenalectomy should receive a steroid substitutive therapy