Endocrine Abstracts

Adrenal mineralocorticoid biochemistry differs between people of African and European ancestry. The aldosterone/renin ratio (ARR) is the initial screening test for primary hyperaldosteronism (PHA), but little data exists regarding ethnic variations in this.

Following clinical observation of a high prevalence of abnormal ARR in patients of African origin, we retrospectively reviewed all ARR measurements in a single centre over 10 years. Rates of hypokalaemia and intraventricular septal thickness (IVS, by echocardiography) were studied as end-points of PHA, and adrenal imaging was reviewed. Data were analysed using Student’s t-test, χ-square test and Mann–Whitney–Wilcoxon test as appropriate.

ARR was available in 1,473 patients, and abnormal in 374 (25.4%). Abnormal ARR occurred in 305/1473 (20.7%) of European and 69/124 (55.6%) of African patients (P<0.001). Among those with abnormal ARR, hypokalaemia (<3.5 mmol/l) was documented on at least one occasion in 171/305 (56.1%) European and 43/69 (62.3%) African patients. Median (range) IVS was 1.57(0.78–2.80) cm in African-origin and 1.2 (0.69–2.18) cm in European patients (P<0.002). Adrenal adenoma was identified in 2/69 (2.8%) African and 41/305 (13.4%) of European patients (P<0.005).

In summary, ARR was abnormal in 55.6% of African-origin patients screened at an Irish hospital, but only 2.8% had demonstrable adrenal pathology. Rates of hypokalaemia were similar between European-origin and African-origin patients, while cardiac hypertrophy was more marked in African-origin patients. These findings have implications for the use of current screening guidelines for ARR in African-origin patients and also for the mechanistic role of aldosterone in hypertensive complications in African-origin patients.