Aims: The Harmonisation of Endocrine Dynamic Testing (HEDTA) guidelines were developed in 2021 to standardise endocrine dynamic testing. We aimed to describe saline suppression test (SST) practices and adherence to HEDTA recommendations at a tertiary referral hospital over a one-year period.

Methods: We performed a retrospective review of all adults (≥18 years) who underwent SST at Concord Repatriation General Hospital in 2024. The department uses the seated SST protocol with 2 L of 0.9% saline infused over 4 hours. [2025/ETH00994].

Results: Twenty-eight patients underwent SST (mean age 51 years, range 30–79; 57% female). Indications included hypertension (78%), elevated aldosterone-renin ratio (75%), adrenal incidentaloma (7%), and hypokalaemia (7%); the indication was undocumented in 14%. Baseline serum potassium was <4.0 mmol/L in 36% of patients, and 7% remained on interfering antihypertensive medication during testing. All patients had post-infusion blood sampling at 4 hours, consistent with HEDTA recommendations. Post-saline aldosterone concentrations were consistent with likely primary aldosteronism in 75%, unlikely primary aldosteronism in 11%, and borderline results in 14%. Among patients with baseline hypokalaemia, only one had a borderline result, which occurred while continuing the interfering medication benidipine; all remaining patients had results consistent with primary aldosteronism. Overall, 50% underwent or were planned for adrenal vein sampling, and 11% underwent or were awaiting adrenalectomy.

Conclusions: Our data demonstrates high adherence to procedural aspects of the HEDTA protocol but identifies deficiencies in pre-test optimisation, particularly correction of hypokalaemia and cessation of interfering medications. Addressing these modifiable factors should improve the accuracy and clinical utility of saline suppression testing for the diagnosis of primary aldosteronism.