A 52-year-old woman comes to the office for follow-up of hypertension. The patient's blood pressure has been stable over the past 8 years on treatment with hydrochlorothiazide and amlodipine. However, recent home blood pressure readings have been higher than usual. The patient has had no changes in sleep quality, caffeine intake, or dietary sodium, but she has been drinking an herbal tea, which her son brought back from a trip to Asia, several times a day. She also takes black cohosh for occasional menopausal hot flashes. The patient does not use tobacco, alcohol, or illicit drugs. Temperature is 36.5 C (97.7 F), blood pressure is 152/88 mm Hg, pulse is 70/min, and respirations are 14/min. Physical examination reveals normal jugular venous pressure, clear lung fields, and normal S1 and S2. Femoral pulses are 2+ bilaterally, and no abdominal bruits are noted. Laboratory results are as follows:
| Sodium | 142 mEq/L |
| Potassium | 3.2 mEq/L |
| Chloride | 96 mEq/L |
| Bicarbonate | 32 mEq/L |
| Blood urea nitrogen | 10 mg/dL |
| Creatinine | 0.8 mg/dL |
Additional testing shows a supine morning plasma renin activity of 0.15 ng/mL per hour (normal: 0.3-1.9) and a serum aldosterone level of 0.9 ng/dL (normal: 2-5). Which of the following is the most likely cause of this patient's uncontrolled hypertension?
Risks of herbal medications | ||
Herbal supplement | Uses | Adverse effects |
Ginkgo biloba |
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Ginseng |
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Saw palmetto |
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Black cohosh |
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St. John's wort |
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Kava |
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Licorice |
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Echinacea |
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Ephedra |
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MI = myocardial infarction; OCs = oral contraceptives. | ||
This patient noticed a significant increase in her blood pressure after she began drinking an herbal tea every day. In addition, she has mild hypokalemia, low aldosterone, and low plasma renin activity (PRA), suggestive of licorice root intoxication.
Licorice root is available as an ingredient in herbal teas and as a flavoring in various food products. However, it contains glycyrrhetinic acid, which inhibits 11-beta-hydroxysteroid dehydrogenase, thereby preventing conversion of cortisol to cortisone. The excess cortisol binds to mineralocorticoid receptors and causes hypertension, hypokalemia, and metabolic alkalosis. Due to feedback inhibition, production of aldosterone and renin is suppressed.
(Choice A) Black cohosh has been promoted for treatment of menopausal symptoms. It is generally safe, although it has been associated with possible hepatotoxicity. In addition, it may cause hypotension (rather than hypertension) and adverse estrogenic effects.
(Choice B) Ginkgo has been marketed as an antioxidant and advocated for the treatment of mild memory loss, dementia, macular degeneration, and peripheral vascular disease. Potential adverse effects include increased risk of bleeding, especially in patients who take aspirin or other antiplatelet drugs.
(Choice D) The clinical manifestations of licorice intoxication are mediated via mineralocorticoid receptors and resemble primary aldosteronism. However, this patient's serum aldosterone level is low.
(Choice E) Renal artery stenosis leads to an elevation in serum aldosterone level due to activation of the renin-angiotensin-aldosterone system. This patient's aldosterone and PRA are low, and the absence of abdominal bruits makes renal artery stenosis even less likely.
Educational objective:
Compounds in licorice root can inhibit the conversion of cortisol to cortisone. The excess cortisol binds to mineralocorticoid receptors and causes hypertension, hypokalemia, and metabolic alkalosis.