Background:
The saline suppression test (SST) is widely used to confirm a diagnosis of primary aldosteronism (PA), but concerns remain about its acute haemodynamic effects, particularly in patients with elevated blood pressure. Limited data is available on its safety, tolerability, and predictors of blood pressure (BP) changes during testing.
Aim:
To assess the safety and tolerability of the SST, evaluate BP changes during the test, and identify patient characteristics associated with BP changes.
Methods:
We conducted a retrospective audit of 419 patients who underwent SST at a tertiary centre between 2019 and 2025. Patients were classified into PA, low-renin hypertension (LRH), or normal-renin hypertension (NRH). PA was defined by post-seated SST aldosterone (immunoassay) >170 pmol/L; LRH by renin <10 mU/L without meeting PA criteria; NRH comprised the remainder. Clinical, biochemical, and BP data were extracted from records. Multiple linear regression identified variables associated with BP changes at 4 hours post-SST.
Results:
The SST was generally safe and well tolerated. Most patients completed the test without adverse events; only one discontinued early, and five required antihypertensives. Mean BP changes did not differ significantly across diagnostic groups. However, PA and LRH patients showed upward systolic BP trends, with 16% and 13% experiencing ≥20 mmHg increases at 4 hours, respectively. In contrast, NRH patients had minimal BP changes. Regression analysis showed higher baseline BP was associated with smaller BP rises (p < 0.001). Older age, higher BMI, and male sex were linked to greater systolic BP increases (p < 0.05).
Conclusion:
The SST appears safe and well tolerated in a referred hypertensive population. BP increases during SST, particularly among PA and LRH patients, may reflect salt sensitivity. Patient factors such as age, sex, BMI, and baseline BP influence haemodynamic responses and may guide patient selection and monitoring.