Resistant hypertension and the neglected antihypertensive: sodium restriction.

Resistant hypertension is defined as blood pressure (BP) that remains above goal (such as 140/90 mmHg or more) in spite of the concurrent use of three antihypertensive agents of different classes. Ideally, one of the three agents should be a diuretic and all agents should be prescribed at optimal dose amounts. Prevalent among 15% of the treated hypertensives, the risk factors for resistant hypertension include older age, chronic kidney disease (CKD), obesity and diabetes mellitus. Causes of resistant hypertension can be classified into four groups: poor adherence, biological-behavioral factors, CKD and secondary causes, and drugs or exogenous substances. However, before labeling the diagnosis of resistant hypertension, it is important to exclude pseudo-resistant hypertension using home BP monitoring in most patients and ambulatory BP monitoring in a few. Before thinking about the next antihypertensive drug, it is important to restrict dietary sodium. Educating the patient on how to interpret the food label and providing feedback by assessing sodium intake with 24 h urine collection are effective sodium restriction strategies. Sodium restriction can lower BP and among patients with proteinuria can even enhance the anti-proteinuric effects of drugs that block the renin-angiotensin system. Sodium restriction is therefore a valuable but a neglected antihypertensive.