Endocrine Abstracts

Introduction: Primary aldosteronism is a clinically significant and treatable cause of hypertension. Diagnosis relies on accurate assessment of the renin-aldosterone axis: both hypokalemia and interfering agents need consideration. In ensuring the necessary conditions are met prior to confirming the diagnosis with a Saline Infusion Test (SIT: gold standard), multiple clinic attendances are often required. Our investigative unit sought to implement a nurse-led protocol to streamline the process.

Protocol: The protocol was implemented in September 2022 for patients undergoing SIT following confirmation of an elevated aldosterone:renin ratio. The following steps are included:

1. Review of baseline renal function and electrolytes.

2. Ensuring interfering agents had been stopped for sufficient time (6 weeks for aldosterone antagonists, 2 weeks for beta blockers, diuretics, angiotensin receptor/ACE inhibitors) and patients changed to doxazosin, verapamil, and/or hydralazine.

3. Blood pressure monitoring 3, 2 and 1 week prior to the test with serum potassium two weeks prior.

Results: We assessed 15 patients prior to implementing the protocol, and 10 patients after (mean age 51 years; 64% male). 32% were prescribed potassium replacement. The average number of day unit visits prior to SIT increased from 1.7 to 2.6. Slightly more patients had sufficient time off polluting agents before the protocol (93% vs 80%). Implementation of the protocol improved the proportion of patients with hypokalemia (<3.5mmol/l) at the time of SIT (22% vs 60%), and significant hypertension (>160/100mmHg) on the day of SIT (10% vs 20%). It also reduced cancellations due to hypertension, hypokalemia or pulmonary oedema (13% vs 20%).

Conclusion: Our nurse-led protocol led to fewer cancellations and more accurate salt load tests, with less hypokalemia. An average of one extra visit per patient was required to achieve this. Overall this creates a safer and more efficient service with appropriately performed and readily interpretable SITs.