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Am Fam Physician. 2001;64(12):2001-2002

Resistant hypertension, defined as failure to lower the blood pressure below 140/90 mm Hg with a maximized three-drug regimen, is relatively common. An organized approach helps physicians identify complicating factors that hinder better blood pressure control. O'Rorke and Richardson review the management of difficult-to-control blood pressure.

Causes of resistant hypertension are listed in the accompanying table. Accurate blood pressure readings require the proper technique and optimal conditions. Blood pressure may rise when patients visit a physician (white coat hypertension) but be under good control at other times. Multiple measurements taken at home or ambulatory blood pressure monitoring can accurately identify this condition. Hypertensive disease progression can occur, especially with aging, making blood pressure control more difficult. Other possible causes for difficult-to-control blood pressure should be considered before the problem is diagnosed simply as disease progression.

Inaccurate blood pressure measurements
White coat hypertension
Disease progression
Suboptimal treatment
Noncompliance with prescribed treatments
Antagonizing substances
Coexisting conditions
Secondary hypertension

Medication regimens may be suboptimal, with some patients requiring multiple medications in addition to diet and exercise instructions. For example, diuretics may be helpful in reducing the fluid retention caused by high dietary salt intake. Poor compliance with a therapeutic regimen can also affect the ability to reach the desired blood pressure goal. Antagonizing substances that raise the blood pressure include nonsteroidal anti-inflammatory drugs, caffeine, erythropoietin, licorice, oral contraceptives, sympathomimetic agents, and medications containing sodium.

Coexisting conditions that may increase blood pressure or negatively affect treatment efficacy include anxiety disorders, hyperinsulinism with insulin resistance, obesity, pain, sleep apnea, and smoking. Patients with secondary hypertension have an underlying disorder, including renovascular disease, pheochromocytoma, and hyperaldosteronism, that is a direct cause of hypertension. These conditions and underlying disorders must be managed to attain better blood pressure control.

O'Rorke and Richardson conclude that physicians should systematically look at the potential causes of difficult-to-control hypertension to successfully manage patients with this condition. This step requires working with patients to learn more about their habits and health activities, evaluating blood pressure monitoring techniques, and seeking a primary cause for secondary hypertension when the initial evaluation is unsuccessful. Referral to a hypertension specialist may be necessary when the cause of poor blood pressure control remains elusive.

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Copyright © 2001 by the American Academy of Family Physicians.

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