The characterisation of phenotypes of patients with essential hypertension (EH) is an important pre-requisite for genetic research. The present study compares clinical and renal function parameters in 2 groups of patients from different origins.
Method: Out of a cohort of essential hypertensives disclosed on routine work medical examinations, 21 caucasian (CC) women were paired with 21 Caribbean (CB) women. In the 2 groups we recorded family history of hypertension (FHH), duration of hypertension, BMI, salt intake based on 24 h urinary sodium excretion, microalbuminuria, and blood pressure (BP). Glomerular filtration rate (GFR) and renal plasma flow (RPF) were measured with inulin and para-amino-hippuric acid clearances. Plasma active renin (AR) and aldosterone (Aldo) levels were measured by immuno-assays. White coat (WC) effect was assessed on the difference between BP values measured on medical visits and by the nurses on clearance measurements. Anova and t-test were used for analysis, statistical significance was assumed for p < 0.05.
Results: Casual BP values were 150/94 mmHg in CB and 153/95 mmHg in CC. There were no significant differences on BMI (CB 30.6 kg/m2 vs CC 27.1 kg/m2). AR (CB 6.6 pg/mL vs CC 8.7 pg/mL) and Aldo (CB 195.1 pmol/L vs CC 202.8 pmol/L) provided an equivalent dietary salt intake (CB 11.2 g/d vs CC 10.7 g/d). Mother FHH was found predominantly in CB women (60% vs 30% in CC, p < 0.05), whereas paternal FHH was more frequent in CC women (21% vs 8% in CB, p < 0.05). At the same age, duration of hypertension was longer by 1 year in CB. White coat effect was more marked in CC (BP > 30 mmHg: 40% in CC vs 5% in CB, p < 0.05). GFR values were normal and similar in CB and CC women. But a significantly lower RPF was measured in CB (489 vs 542 mL/min/1.73 m2 in CC, p < 0.05). Higher filtration fraction and microalbuminuria were also observed in CB women.
Conclusion: Essential hypertension occurs at younger ages in Caribbean women. The decrease in RPF could be genetically determined and is likely to participate in early onset of hypertension, as previously described in young normotensive subjects. In paired women, we did not found significant differences in active renin and aldosterone levels. The ongoing longitudinal study should contribute to assess the consequences of these findings on renal prognosis and the effects of antihypertensive therapy.