Effect of Oral Contraception on Screening Tests for Primary Aldosteronism: a 10-year Longitudinal Study

Primary aldosteronism (PA) and oral contraception (OC) can both cause hypertension in young women. However, the effect of OC on the screening test for PA, the aldosterone to renin ratio (ARR), is not clear. The objective of the study was to evaluate the impact of OC on the screening test for PA. We analysed data from the female offspring (Gen2) of women enrolled in the Raine Study, a population-based birth cohort, who had BP measurements, blood samples and information about OC use at age 17y (N = 484) and/or age 27y (N = 486). Aldosterone concentration was significantly higher in OC users than non-users at 17y (median 486 pmol/L vs 347 pmol/L, p < 0.001). Renin concentration was significantly lower in OC-users at both 17y (13.4 mU/L vs 20.6 mU/L) and 27y (9.2 mU/L vs 11.8 mU/L), hence the ARR was significantly higher in OC-users compared to non-users at both 17y (31.5 vs 18.3) and 27y (27.3 vs 21.1). The proportion of participants with ARR > 70 pmol/mU (current threshold for PA detection) was significantly higher in OC-users at both 17y (12.6% vs 2.1%) and 27y (6.4% vs 0.4%), however, they had comparable BP to those with ARR < 70. OC use at any age abolished the relationship between ARR and BP that is observed in non-OC users. OC can increase the ARR and cause a false positive PA screening result. Until more reliable criteria for PA screening in OC users are established, alternative contraception should be considered during screening.