Cardiovascular Journal of Africa: Vol 31 No 3 (May/June 2020)

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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 31, No 3, May/June 2020 130 AFRICA
A primary aldosteronism-like phenotype identified with
the aldosterone-to-angiotensin II ratio in black men:
the SABPA study
Johannes M van Rooyen, Marko Poglitsch, Hugo W Huisman, Lebo F Gafane-Matemane, Yolandi
Breet, Leonè Malan
Abstract
Introduction: Black populations may be more likely to have
primary aldosteronism (PA) due to adrenal hyperplasia or
other forms of adrenal hyperactivity, with suppressed renin
levels and high levels of aldosterone, which may contribute to
the development of hypertension.
Methods: This sub-study involved 35 black men matched
for age, gender and race, and aged 20–65 years, living in the
North West Province of South Africa. RAAS triple-A analy-
sis was carried out with LC-MS/MS quantification. Blood
pressure, electrocardiography and other variables were deter-
mined with known methods.
Results: Hypertensive subjects with higher aldosterone levels
showed an increased aldosterone–angiotensin II ratio (AA2
ratio) compared to the hypertensive subjects with low aldos-
terone levels (10.2 vs 3.0 pmol/l; p = 0.003). The serum potas-
sium concentration was significantly lower in the high-aldos-
terone group and the serum sodium–potassium ratio was
significantly higher compared to the low-aldosterone group
(3.9 vs 4.5, p = 0.016, 34.8 vs 31.8, p = 0.032, respectively).
Furthermore, aldosterone was positively associated with both
left ventricular hypertrophy (Cornell product) (Spearman R =
0.560; p = 0.037) and kidney function [albumin-to-creatinine
ratio (ACR)] (Spearman R = 0.589, p = 0.021) in the hyper-
tensive high-serum aldosterone group.
Conclusions: The AA2 ratio, a novel screening test that is
currently being validated for PA case detection, was used to
identify a PA-like phenotype in black men. Excess aldosterone
was associated with endothelial dysfunction and left ventricu-
lar hypertrophy, independent of blood pressure.
Keywords: aldosterone, hypertension, organ damage, RAAS, blacks
Submitted 13/8/19, accepted 2/10/19
Published online 27/11/19
Cardiovasc J Afr 2020; 31: 130–135
DOI: 10.5830/CVJA-2019-059
Although the incidence of high blood pressure has decreased
worldwide since 1975, a shift is reported fromhigh- to low-income
countries, such as those in sub-Saharan Africa.1,2 In blacks,
hypertension is characterised by a greater retention of salt
and water by the kidney, with suppressed levels of renin and
aldosterone. 3 Black populations may also be more likely to have
primary aldosteronism (PA) due to adrenal hyperplasia or other
forms of adrenal hyperactivity, with suppressed renin levels and
high levels of aldosterone. 3,4
Furthermore, black populations may also have a greater
sensitivity of blood pressure to the increased secretion of
aldosterone and are more likely to have hypertension.5 PA is an
overlooked but frequent cause of secondary hypertension. In a
recent survey in Italy and Germany, it was found that only 7–8% of
general practitioners ordered aldosterone and renin measurements,
and the prevalence of diagnosed PA was only 1% of hypertensive
patients.6 The consequence is that only 1% of patients in Italy
and 2% in Germany are diagnosed with the disease. From recent
studies, a prevalence approaching 5–13% was found.7-9
From the literature, it seems that PA is a largely unrecognised
and undertreated cause of hypertension. In South Africa, the
case may not be different due to the fact that awareness (27%),
treatment (18%) and control rates (7%) for hypertension are low.2
PA is also a common occurrence in resistant hypertension and
screening for it may improve hypertension treatment, which is
already a challenge in South Africa.
We therefore aimed to evaluate the role of aldosterone as a
contributory factor in hypertension in a black cohort by identifying
a PA-like phenotype with the use of the novel aldosterone–
angiotensin II ratio (AA2 ratio). One parameter obtained in
RAAS triple-A testing, the simultaneous LC-MS/MS-based
quantification of angiotensin I (Ang I), angiotensin II (Ang II)
and aldosterone, was obtained in patient samples. Concerns are
raised about the accuracy of renin assays and therefore new mass
spectrometric methods were employed for measuring angiotensin
II, which are currently being assessed in the clinical setting.
Methods
The baseline Sympathetic Activity and Ambulatory Blood
Pressure in Africans (SABPA) study was conducted in the North
Hypertension in Africa Research Team (HART), North-West
University, Potchefstroom, South Africa
Johannes M van Rooyen, DSc,
Hugo W Huisman, PhD
Lebo F Gafane-Matemane, PhD
Yolandi Breet, PhD
Leonè Malan, PhD
South African Medical Research Council: Unit for
Hypertension and Cardiovascular Disease, North-West
University, Potchefstroom, South Africa
Johannes M van Rooyen, DSc
Hugo W Huisman, PhD
Lebo F Gafane-Matemane, PhD
Yolandi Breet, PhD
Leonè Malan, PhD
Attoquant Diagnostics, Vienna, Austria
Marko Poglitsch, PhD