Primary aldosteronism (PA) is the most common endocrine cause of hypertension and is associated with increased cardiovascular and renal morbidity. The aldosterone-renin ratio (ARR) is the recommended screening test for PA; however, interpretation may be affected by commonly used antihypertensive medications. In the absence of relevant clinical information accompanying pathology requests, laboratories are generally limited to providing generic comments rather than patient-specific guidance. To address this gap, we developed a web-based clinical decision support tool to facilitate contextualised interpretation of the ARR.
With support from the Endocrine Society of Australia (ESA) and the Australasian Association for Clinical Biochemistry and Laboratory Medicine (AACB), the Primary Aldosteronism Clinical Tool (PACT) was developed and deployed on the ESA website. Decision rules were derived from contemporary literature and international guidelines on PA diagnosis and management.1,2 The algorithm incorporates aldosterone assay and units, renin units, ARR reference intervals, hypokalaemia, aldosterone thresholds, medication effects on ARR, and recommendations regarding repeat testing, medication optimisation and specialist referral. The tool accommodates commonly prescribed and newer medications which affect the ARR, including sodium-glucose cotransporter-2 inhibitors.
PACT provides contextualised interpretations rather than reporting a numerical ARR alone. Depending on the biochemical and clinical settings, outputs may identify likely PA despite interfering medications, recognise circumstances in which the ARR may be falsely elevated or suppressed, recommend correction of hypokalaemia, suggest medication switching and repeat testing, or prompt specialist referral.
PACT translates complex, context-dependent ARR interpretation into a clinician-facing digital decision support tool that is publicly accessible through the ESA website. Such an approach has the potential to improve the consistency of ARR interpretation, avoid unnecessary medication changes, rationalise the use of downstream testing, reduce time to diagnosis, and provide a model for translating clinical guidelines into digital clinical decision support tools.