Renin Activity and Aldosterone Assay Among Nigerians with Hypertension and Normotension: An Insight into Normative Values and Clinical Correlates.

Objectives: Plasma renin activity (PRA) and aldosterone tend to differ between Blacks and Caucasians and studies are very scarce among Africans. We therefore aimed to determine the normative value of plasma renin activity and serum aldosterone among school teachers in Nigeria with normal blood pressure compared with their hypertensive counterparts and relevant clinical/ demographic associations.

Methods: Plasma renin activity and serum aldosterone were measured using the kits provided by Diagnostic Biochem, Canada among randomly selected school teachers recruited as part of a study to assess their total cardiovascular risks. Mean serum values were compared between normotensive and hypertensive participants and were correlated with clinical and demographic parameters. Statistical analysis was done using SPSS 17.0, Chicago, Ill, USA. P <0.05 was taken as statistically significant.

Result: The mean PRA level of all study participants was 0.80 ± 0.85 ng/mL.h (mean ± SD) while the mean serum level of aldosterone was 93.9 ± 60.9 pg/ml. The mean aldosterone: renin ratio was 446.5 ± 958.2. The frequency of occurrence of hypertension was 29%. Only plasma renin activity was significantly correlated with systolic and diastolic blood pressure, age and the rate pressure product (a measure of cardiovascular risk). The finding of a higher mean PRA among hypertensive subjects is definitely related to the antihypertensive medications being taken including beta blockers and angiotensin converting enzyme inhibitors among others. The prevalence of high aldosterone/ renin ratio which could reflect the proportion of primary aldosteronism was 10.8%.

Conclusion: Nigerians have a low renin activity compared to their Caucasian counterpart. PRA may be an important determinant of blood pressure among Nigerians. Appropriate drugs that target phenotypic status of PRA and aldosterone may be useful in the management of hypertension and the choice of pharmacotherapy among Nigerians.