Resistant hypertension is a failure to achieve goal BP (<140/90？mm？Hg for the overall population and <130/80？mm？Hg for those with diabetes mellitus or chronic kidney disease) in a patient who adheres to maximum tolerated doses of 3 antihypertensive drugs including a diuretic. The kidneys play a critical role in long-term regulation of blood pressure. Blunted pressure natriuresis, with resultant increase in extracellular fluid volume, is an important cause of resistant hypertension. Activation of the renin-angiotensin-aldosterone system, increased renal sympathetic nervous system activity and increased sodium reabsorption are important renal mechanisms. Successful treatment requires identification and reversal of lifestyle factors or drugs contributing to treatment resistance, diagnosis and appropriate treatment of secondary causes of hypertension, use of effective multidrug regimens and optimization of diuretic therapy. Since inappropriate renal salt retention underlies most cases of drug-resistant hypertension, the therapeutic focus should be on improving salt depleting therapy by assessing and, if necessary, reducing dietary salt intake, optimizing diuretic therapy, and adding a mineralocorticoid antagonist if there are no contraindications. 1. Introduction The Joint National Committee (JNC) 7 defined resistant hypertension as failure to achieve goal blood pressure (BP) (<140/90？mm？Hg for the overall population and <130/80？mm？Hg for those with diabetes mellitus or chronic kidney disease) in a patient who adheres to maximum tolerated doses of 3 antihypertensive drugs including a diuretic. An increasing number of patients, especially the aged, those with diabetes or who are African American, meet this definition. However, it is important to rule out white coat hypertension by asking the patient to record their own home blood pressures and undertaking an ambulatory blood pressure monitor if the results are equivocal. A careful enquiry about whether the patient is taking the prescribed medications and if there are adverse effects that are causing concern may give clues to noncompliance. In some cases, it may be useful to measure blood or urine drug levels, for example of diuretics, to check for noncompliance. A recent study of African Americans with hypertensive focal segmental glomerulosclerosis [1] has linked a single nucleotide polymorphism for the apolipoprotein L1 gene to the disease but this is not yet available as a diagnostic test. Since aging increases the burden of vascular disease, resistant hypertension and its consequences are more common in
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