Poster Presentation The Joint Annual Scientific Meetings of the Endocrine Society of Australia and the Society for Reproductive Biology 2017

Can the saline suppression test predict the subtype of primary aldosteronism? (#217)

Hikaru Hashimura 1 , Jimmy Shen 1 , Peter Fuller 1 , Nicholas Chee 1 , James Doery 2 , Winston Chong 3 , Kay Weng Choy 2 , Stella Gwini 4 , Jun Yang 1
  1. Endocrinology, Monash Health, Clayton
  2. Pathology, Monash Health, Clayton
  3. Radiology, Monash Health, Clayton
  4. Monash Health Translational Precinct, Monash University, Clayton


The saline suppression test (SST) is conducted to confirm the diagnosis of primary aldosteronism (PA) in patients with an elevated aldosterone:renin ratio. Studies have speculated that SST can predict PA subtype as either unilateral (predominantly an aldosterone-producing adenoma) or bilateral (adrenal hyperplasia) [1].  An accurate prediction of bilateral disease may reduce the need for adrenal vein sampling (AVS).


To identify SST parameters that distinguish bilateral from unilateral PA.


A retrospective analysis was performed on 89 patients who underwent the SST at Monash Health (February 2011 - May 2017). Clinical information collected included patient demographics, SST, AVS and histology results. A positive SST was defined as plasma aldosterone concentration (PAC) >140pmol/L at 4 hours post-infusion of 2L normal saline in the recumbent position [2].  Patients with positive SST results were categorized into three PA subtypes: unilateral, bilateral and undetermined (unsuccessful AVS or no AVS). Results were expressed as median (lower and upper quartiles).


84 patients had a positive SST: 25 unilateral, 25 bilateral and 34 undetermined. The unilateral group had significantly higher PAC compared to the bilateral group both at 0 hours, 538 pmol/L (441-748) vs 323 pmol/L (250-429) (p=0.004), and at 4 hours, 462 pmol/L (280-764) vs 230 pmol/L (195-298) (p=0.05).

Compared to the bilateral group, the PAC in the unilateral group demonstrated a lower absolute reduction at 4 hours, -69 pmol/L (-178-30) vs -87 pmol/L (-142--44) and a smaller percentage decrease at 4 hours, -17% vs -27%, however these were not statistically significant.


Unilateral causes of PA had a higher PAC during the SST both at 0 and 4 hours. However, we did not identify a clear SST parameter which differentiated unilateral from bilateral PA. A seated SST which is more sensitive for bilateral PA [3] may be better for predicting PA subtypes.

  1. References: 1. Rossi GP,, Prospective evaluation of the saline infusion test for excluding primary aldosteronism due to aldosterone-producing adenoma. Journal of Hypertension, 2007. 25: 1433-42. 2. Funder JW, Young WF,, The management of primary aldosteronism: case detection, diagnosis and treatment: An endocrine society clinical practice guideline, 2016. 101: 1889-1916. 3. Ahmed AH, Stowasser M,, A seated saline suppression testing for the diagnosis of primary aldosteronism – a preliminary study. J Clin Endocrinol Metab, 2014. 99(8): 2745-53.