The aim of this study was to determine the prevalence of secondary hypertension in a population of refractory hypertension without initial clinical or biological findings suggesting identifiable causes of hypertension.
Methods: A survey included 200 consecutive hypertensive patients referred to hypertension specialists for refractory hypertension (BP > 140/90 mmHg on at least two antihypertensive drugs). Prior inclusion, the permanent elevation of blood pressure was confirmed by ambulatory monitoring. In each subject an extensive work-up was performed to detect a secondary cause for hypertension.
Results: An essential hypertension was confirmed in 61% of this cohort. A secondary hypertension was detected in 20% of the patients; 8.5% with a primary hyperaldosteronism, 8% with a reno-vascular hypertension and 3% with a nephropathy. Moreover, 18.5% had a low renin hypertension. Thus, 27% of these patients had an abnormality of the renin-aldosterone axis.
Conclusion: Patients with refractory hypertension should be explored to detect secondary hypertension even without findings suggesting such causes. This additional diagnostic procedure must include at least renovascular investigations and plasma renin/aldosterone level determinations in appropriate conditions.