Endocrine Abstracts

Introduction: Adrenal venous sampling (AVS) is considered the reference standard to select patients with unilateral aldosterone producing adenoma for adrenalectomy. Recent studies debated the “mandatory” need for AVS before adrenalectomy. We report our experience from a tertiary hospital in Asia on the treatment outcomes of patients with primary aldosteronism (PA) who underwent adrenalectomy without AVS compared to those who had successful AVS.

Methods: A retrospective review of patients with PA who underwent adrenalectomy from February 2008 to July 2017 in Singapore General Hospital was conducted. All patients had positive case detection as defined by screening plasma aldosterone concentration (PAC): plasma renin activity (PRA) or active renin (DRC) of >20 or >3.8 respectively. They were further confirmed with intravenous salt loading test, with post infusion PAC >10 ng/dl (277 pmol/l). All patients with confirmed PA underwent adrenal CT scan. Clinical characteristics, CT findings and AVS results were analysed.

Results: In the entire cohort, 63.9% of patients had hypertension, 72.2% had hypokalemia and 16.7% had adrenal incidentaloma. Twenty three patients (63.9%) who underwent adrenalectomy had successful AVS while 13 patients (36.1%) were based on CT findings. The patients who underwent adrenalectomy based on AVS were older compared to those who did not have AVS, with mean age of 50.8 years and 45.9 years respectively. There was no significant difference in the level of hypokalemia in the AVS compared to the non-AVS group (2.7 mmol/l vs 2.9 mmol/l, P=0.709). Non-AVS based adrenalectomy group had an overall larger adrenal adenomas compared to the AVS based adrenalectomy group (2.23 cm vs 1.36 cm, P=0.013). There was no significant difference in the number of antihypertensive medications required prior to adrenalectomy in the non-AVS vs the AVS group (1.69 vs 2.17, P=0.991). When comparing between the non-AVS and the AVS-based adrenalectomy group, there was no significant difference in the patients who had complete resolution of hypertension (66.7% vs 45.5%, P=0.678) nor any difference in the reduction of anti HTN medications (45.5% vs 36.4%, P=0.079). In the non-AVS group, the factors associated with improvement in hypertension, were age <45 years (P=0.014), adrenal adenoma size ≥1.3 cm with contralateral normal adrenal gland on CT scan (P=0.028) and K<3.2 mmol/L (P=0.028). Among those did not experience improvement in hypertension after adrenalectomy, all were > 45 years old.

Conclusion: Where access to expert AVS is limited, adrenal CT combined with specific clinical and biochemical features can potentially safely select patients for adrenalectomy.