ABSTRACT Retrospective analysis of treated
primary aldosteronism in a single centre hypertensive cohort Background/Aims: There is wide variation in the estimated prevalence of primary aldosteronism (PA) amongst hypertensive patients in the literature, ranging from 3% up to 20% (Galati et al 2013, Chao et al 2016). Our aim was to determine the prevalence of treated PA in a local hypertensive population using an aldosterone-renin ratio (ARR) as the initial screening test. Methods: All ARRs performed at Canterbury Health Laboratory from 1/6/14 to 31/12/15 were obtained. Patients under 18 and/or those with pre-existing adrenal pathology were excluded. Prevalence of treated PA in those with an abnormal ARR on any combination of antihypertensive medications was estimated. The cut-off value for an abnormal ARR was greater than 30.5 ng/dl per ng/ml/h when the serum aldosterone is above 250 pmol/l. Results: During the 18 months, 177 hypertensive patients had an ARR. The male:female ratio was 0.82 and the mean age 53.2 ± 16.8 years. An abnormal ARR was found in 36/177 (20.3%). Saline suppression testing was performed on 15/36 patients, with 2 positive results. Of the 21 remaining, 3 were treated as PA on clinical grounds. The prevalence of treated PA in this cohort is 5/177 (2.8%). Conclusion: The prevalence of treated PA in our local hypertensive cohort is lower than that reported in the literature.
Possible reasons include a higher threshold to screen patients, higher cut-off value for an abnormal ARR, false negatives with certain antihypertensive medications, and a proportion of those with abnormal ARRs had no confirmatory testing. It would be interesting to establish the true prevalence of PA in this cohort without confounding medications. References:
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