Aim: Recent studies reported a wide range in baseline and peak cortisol responses to surgery. We report the results of cosyntropin stimulation testing following unilateral adrenalectomy for non-steroid secreting lesions.
Methods: Data of 36 patients who underwent cosyntropin stimulation testing on the second day post unilateral adrenalectomy were collected retrospectively. None of the patients had clinical signs of hypercortisolism. No patient received pre- or intraoperative steroids. A stimulated plasma cortisol of ≥450 nmol/l at 30 min was regarded as normal (Abbott Architect assay).
Results: The median age was 58 (3179) years. Preoperatively, 16 (44.44%) patients had a diagnosis of phaeochromocytoma, 12 (33.33%) had primary aldosteronism and 8 (22.22%) had non-functioning lesions. Preoperative overnight dexamethasone suppression test (ONDST) results were available for 29 patients. Morning cortisol post-ONDST was ≤50 nmol/l, 51138 nmol/l and >138 nmol/l in 23 (79.31%), 5 (17.24%) and 1(3.45%) patients respectively. 20 (55.56%) patients achieved a stimulated cortisol ≥450 nmol/l at 30 min and 28 (77.78%) at 60 min. Mean baseline cortisol levels were significantly higher in those who passed the cutoff than in those who did not. No difference was observed in age, lesion size, diagnosis, ONDST results or incremental increase of 150 nmol/l from baseline to 30 min. Using a lower cutoff of 375 nmol/l, 28 (77.78%) patients passed at 30 min and 33 (91.67%) at 60 min. However, only one patient required postoperative steroid replacement.
Conclusions: This study shows that using standard dynamic cortisol test cutoffs following unilateral adrenalectomy would label almost one third of patients as adrenally insufficient, most of whom do not require steroid replacement. Therefore, cosyntropin stimulation testing following unilateral adrenalectomy needs to be interpreted in the clinical context taking into account variable cortisol responses, improved cortisol assays and improved surgical techniques.