Secondary hypertension may often be caused by renal artery stenosis, chronic kidney disease, Cushing syndrome, pheochromocytoma, primary aldosteronism, sleep apnea, and in rare cases the syndrome of apparent mineralocorticoid excess (AME). A genetic mutation can result in AME although it can be acquired with chronic ingestion of glycyrrhizic acid, an ingredient found in pure licorice. While the latter is not often found to be the cause of secondary hypertension, a case published in The Journal of Clinical Hypertension demonstrates why it should still be considered in the differential diagnosis.
The patient, a 50-year-old woman, presented to an outpatient clinic with headaches, muscular leg pain, palpitations, and blood pressure (BP) readings of over 200/100mmHg, but no shortness of breath, chest pain, or peripheral edema. Three years prior when she first came to the clinic, her baseline BP had been 120/70mmHg with no family history of hypertension. Her other medical history included menstrual migraines and kidney stones; she denied tobacco or recreational drug use and consumed no more than two glass of wine/week.
To manage the hypertension, clinicians started the patient on lisinopril 10mg daily. One week later, when she returned for follow-up, her BP reading was 220/110mmHg at which point she was started on amlodipine 10mg and potassium chloride 60mEq (for myalgia) in addition to the lisinopril. Following this visit, labs were ordered and the results showed the following:
- Sodium: 146mEq/L (normal: 137–144)
- Potassium: 2.9mEq/L (normal: 3.6–5.1)
- Serum aldosterone: <3.0ng/dL (normal for those over 15 years old: 4–31)
- Renin: 0.2ng/mL/h (normal: 0.2–1.6)
- Parathyroid hormone: 105pg/mL (normal: 15–88)
- Ionized calcium: 1.25mmol/L (normal: 1.14–1.33)
- Thyroid-stimulating hormone: 1.67mIU/L (normal for those over 20 years old: 0.40–4.50)
The patient came back to the clinic four days later for follow-up at which point her BP was 174/82mmHg prompting an increase in her lisinopril dose to 40mg daily. Urinalysis was ordered and the test revealed elevated levels of total free cortisol (170.26µg/g Cr [normal: <24µg/g Cr]). After reviewing her dietary history, it was revealed that the patient consumed multiple cups of Egyptian Licorice tea (bought in the U.S.) on a daily basis (4–5 cups) which contained pure licorice root (Glycyrrhiza glabra). The patient was advised to stop drinking the tea immediately, to continue her lisinopril dose of 40mg daily but to discontinue treatment with amlodipine.