FRI121 Markers Of Primary Aldosteronism In An Indigenous Australian Birth Cohort

Disclosure: E. Ng: None. S. Gwini: None. M. Stowasser: None. M.J. Young: None. P.J. Fuller: None. G.R. Singh: None. J. Yang: None. Primary aldosteronism (PA) is the most common endocrine cause of hypertension and a highly modifiable risk factor for cardiovascular disease (CVD). In PA, excess production of aldosterone leads to downregulation of renin and an elevated aldosterone-to-renin ratio (ARR). There are no data on aldosterone and renin profiles in Indigenous Australians despite their high rates of hypertension and CVD. Hence, we evaluated the prevalence of an abnormal ARR and the relationship between aldosterone, renin, ARR, and blood pressure (BP) in participants of the Aboriginal Birth Cohort (ABC) compared to age-matched non-Indigenous participants of the Top End Cohort (TEC). The ABC is the largest and longest running cohort of Aboriginal people in Australasia who have comprehensive health checks every 5-7 years with an overall aim of relating early life events to later health. Participants of the ABC were located in both urban and remote regions of the Northern Territory while the TEC was entirely urban. These results represent data collected between 2019 to 2021, when both cohorts were 32-35 years of age. Aldosterone and renin levels were measured by immunoassay. There were 255 participants in the ABC (205 remote, 50 urban) and 76 in the TEC. Aldosterone levels were similar while renin was lowest in TEC (7.5 mU/L) compared to the urban ABC (12.4 mU/L) (p=0.035) and remote ABC (29.3 mU/L) (p<0.001). Within the ABC, renin was lower in the urban cohort compared to the remote cohort (p<0.001). Median ARR was lowest in the remote ABC (10 pmol/LmU/L) compared to the urban ABC and TEC (ARR 28 and 43 pmol/LmU/L, respectively, p<0.001 when each compared to remote ABC, p=0.057 for urban ABC compared to TEC). There was a high prevalence of abnormal ARR (>70 pmol/L:mU/L) in both the urban ABC and TEC (26% and 28%, respectively), compared to only 3% in the remote ABC. The lower prevalence of ARR > 70 in the latter may be due to cryoactivation falsely elevating renin as transport on ice was required for samples from the remote ABC but not for urban ABC or TEC. Male sex, waist circumference and BMI were significantly positively associated with SBP and DBP in all cohorts while the ARR was positively associated with SBP in the TEC, but not in the ABC. This is the first study to examine aldosterone and renin in indigenous Australians. The finding of an abnormal ARR in over a quarter of the urban ABC and TEC suggests that the prevalence of PA is likely high and independent of indigenous status. The effect of cryoactivation on samples from remote regions may have masked abnormal ARR and a potential relationship between ARR and SBP, in contrast to the TEC where ARR was associated with increasing SBP. The data suggest that Indigenous Australians would benefit from adequate access to PA testing using accepted standards. Further evaluation with appropriate sample handling is warranted to appreciate the true prevalence of PA in this population. Presentation: Friday, June 16, 2023