Endocrine Abstracts

Introduction: Primary aldosteronism (PA) is the most common endocrine cause of hypertension affecting up-to 10% of hypertensives. Saline suppression, a confirmatory test for PA helps avoiding patients undergoing invasive lateralisation procedures due to a false positive aldosterone-to-renin ratio (ARR). The proposed cut-off to exclude PA is post-saline aldosterone suppression to <140 pmol/l. We reviewed our biochemical work-up in order to optimise laboratory assessment.

Method: This retrospective audit reviewed adult patients who underwent saline suppression test between January 2014 and December 2015. Pathology and hospital IT systems were used to obtain relevant information (investigations, multi-disciplinary meeting (MDM) outcomes, histology and management).

Results: In total there were 54 patients (26M) aged 51 (43–59) (median (IQR)) years. Based on exclusion criteria three had post-saline aldosterone <140 pmol/l (CT scan – 2 normal and 1 adenoma) and were medically managed. MDM diagnosed PA in 37 (post-saline aldosterone >140 pmol/l) out of which 21 were managed surgically. 19, histology confirmed PA had pre and post-surgery (1–8 weeks after surgery) saline suppression. After surgery, baseline and post-saline aldosterone decreased from 831 (556–1223) to 232 (139–288) and 716 (469–1000) to 121 (89–151) pmol/l respectively (both, P<0.0001). Only 12 suppressed to <140 pmol/l, the other seven suppressed between 140 and 233 pmol/l. The post-surgery aldosterone suppression was 81 (range 62–96)%.

Conclusion: In our cohort the proposed post-saline aldosterone cut-off <140 pmol/l correctly identified all patients with conformed PA but, only 63% had post-saline aldosterone <140 pmol/l after surgery. However, all had >60% reduction in post-saline aldosterone. Larger studies are needed to standardise biochemical confirmation of successful surgical resection of PA.