A 23-year-old woman with no other past medical history was diagnosed with hypertension 6 months ago. She was initially treated with hydrochlorothiazide, followed by the addition of lisinopril, followed by high doses of a beta-blocker, but her blood pressure has not been well controlled. She assures the provider that she is taking all of her medicines. On examination her blood pressure is 165/105 in each arm, and 168/105 when checked by large cuff in the lower extremities. Her pulse is 60. Cardiac examination reveals an S4 gallop but no murmurs. She has a soft mid-abdominal bruit. Distal pulses are intact and equal. She does not have hyperpigmentation, hirsutism, genital abnormalities, or unusual distribution of fat. Her sodium is 140, potassium 4.0, HCO3 22, BUN 15, and creatinine 1.5.
Which of the following is the most likely cause of her difficult-to-control hypertension?A) Primary hyperaldosteronism (Conn syndrome)
This patient is young to have developed hypertension, and the finding of renal bruits is highly suggestive of a secondary cause of the condition: renal artery stenosis caused by fibromuscular dysplasia (FMD). FMD is more common in young females (85%-90% of cases are in females in some series). The exact etiology of the condition is unknown, but renal artery stenosis causing hypertension is a common presentation. Digital subtraction angiography is the diagnostic modality of choice though duplex ultrasonography, CT angiography, and MR angiography can also be utilized. Etiologies that can mimic fibromuscular dysplasia include atherosclerosis and vasculitis. The patient has no physical findings to make one suspect Cushing syndrome (abnormal fat distribution, ecchymoses, hirsutism, etc), congenital adrenal hyperplasia (virilization), or coarctation of the aorta (BP lower in legs than in arm). She does not have the metabolic alkalosis and hypokalemia of primary hyperaldosteronism.