Endocrine Abstracts

Objective: Primary aldosteronism (PA) is a common cause of secondary hypertension. Antihypertensive agents interfere with the renin-angiotensin-aldosterone axis, and screening with the aldosterone to renin ratio (ARR) is preferably made without medication. Withdrawal may however be harmful. We examined the detection rate of PA in hypertensive patients taking their prescribed medication, apart from amiloride and spironolactone.

Design and setting: Hypertensive patients recruited from a primary care unit were investigated in a university hospital setting. The cut-off level for a positive ARR, indicative of PA, was set at >50 pmol/ng with aldosterone >350 nmol/l which is lower than practise to minimize false negatives. A positive ARR was followed by a confirmatory evaluation.

Subjects: 233 hypertensive patients aged 25 to 70 were recruited and 78% agreed to participate. The majority had at least two antihypertensive agents.

Results: The frequency of confirmed PA was 1.6% and including cases with positive ARR who refused further investigation it would be 3.3% at most. In primary hypertension ARR decreased with the number of antihypertensive agents used due to increasing renin. Compared to untreated patients, median ARR was reduced by approximately 70% when taking 3 or 4 agents. Angiotensin receptor blockers, ACE inhibitors and thiazide diuretics markedly suppressed the ARR.

Conclusion: The low detection rate of PA does not support screening in the general hypertensive population. The marked suppression of ARR by antihypertensive drugs indicates that other cut-off levels should be defined for patients on treatment. At present, screening for PA should be carried out as far as possible without medication.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This work was supported, however funding details unavailable.