How Should I Approach a Patient with Resistant Hypertension?
MARCH 11, 2014
Karol Watson, MD
You see a 60-year-old African-American female patient for the first time for an annual checkup. Her past medical history is notable only for a 15-year history of hypertension and a history of having undergone a diagnostic laparoscopy 30 years ago for infertility. Her current medications are hydrochlorothiazide 25 mg daily, valsartan 320 mg daily, and amlodipine 10 mg daily. Physical examination is remarkable for a blood pressure of 177/90 mm Hg, pulse of 67 bpm, and a body mass index (BMI) of 28.41 kg/m2.
While the patient’s lung exam is clear, her fundoscopic exam reveals arteriovenous (AV) nicking and her heart exam is notable for the presence of an abnormal diastolic heart sound (S4). However, she has no flank or epigastric bruits.
The patient reports that over the past year, her blood pressure has consistently been >150/95 mm Hg when checked at the doctor’s office.
Does she qualify for the diagnosis of resistant hypertension?
According to the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC 7), resistant hypertension is defined as the failure to achieve a blood pressure of at least 140/90 mm Hg — or at least 130/80 mm Hg for patients with diabetes or renal disease — despite adherence to treatment with full doses of at least 3 antihypertensive medications, including a diuretic. So, by that definition, this patient does have resistant hypertension.
The true prevalence of resistant hypertension is unknown, but it is estimated to occur in up to 20% of patients with chronic hypertension. Older age, obesity, and high baseline systolic blood pressure are among the strongest risk factors for resistant hypertension. In addition, African-American patients and women are more likely to have resistant hypertension.
What are possible causes of resistant hypertension?
In general, cases of resistant hypertension can be grouped into:
- Patient-related causes, such as non-adherence to medications
- Physician-related causes, such as failure to titrate medications
- Interfering substance, such as excessive salt intake
- Secondary hypertension, such as obstructive sleep apnea (OSA)
Drugs that lead to salt and water retention are among the most common causes of drug-induced resistance. Therefore, non-steroidal anti-inflammatory drugs (NSAIDs), glucocorticoids, and oral contraceptives are common causes of drug-induced resistant hypertension. Another class of medications that may induce hypertension is the sympathomimetic agents, which are found in many over-the-counter cold preparations or diet pills.
The patient states that she rarely forgets to take her medication, but when she does, it is generally when she goes on vacation. She said she tries to watch the salt in her diet and only occasionally uses the saltshaker to season her food. How would you evaluate her salt intake?
If you suspect the patient is ingesting excessive sodium, this can be assessed via 24-hour urine collection. The amount of sodium needed for normal physiologic functioning is small, yet humans typically ingest sodium in much larger amounts. Under normal conditions, the kidneys serve as the sole mode of excretion of excess sodium. Therefore, the amount of sodium excreted in a 24-hour period is a very good estimate of the amount of sodium ingested.1 If, in fact, sodium excess is contributing to this patient’s resistant hypertension, then blood pressure control can be improved with firm sodium restriction.
What dietary and lifestyle instructions would you offer this patient?
Lifestyle modification has been shown to be a very successful treatment for hypertension or prehypertension. According to the JNC 7, appropriate modifications include reducing dietary sodium to <2.4 g per day; increasing exercise to at least 30 minutes per day for 4 days a week; limiting alcohol consumption to 2 drinks or less per day for men, or 1 drink or less per day for women; following the Dietary Approaches to Stop Hypertension (DASH) eating plan, which is high in fruits, vegetables, potassium, calcium, and magnesium, but low in fat and salt; and achieving a weight loss goal of 10 lbs or more.