MEDizzy - A 28-year-old woman has hypertension that is difficult to

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Disorders of the cardiovascular system 2

A 28-year-old woman has hypertension that is difficult to control. She was diagnosed at age 26. Since that time, she has been on increasing amounts of medication. Her current regimen consists of labetalol 1000 mg twice a day (bid), lisinopril 40 mg once a day (qd), clonidine 0.1 mg bid, and amlodipine 5 mg qd. On physical examination, she appears to be without distress. Blood pressure is 168/100 mmHg, and heart rate is 84 bpm. A cardiac examination is unremarkable, without rubs, gallops, or murmurs. She has good peripheral pulses and no edema. Her physical appearance does not reveal any hirsutism, fat maldistribution, or abnormalities of genitalia. Laboratory studies reveal a potassium of 2.8 mEq/dL and a serum bicarbonate of 32 mEq/dL. Fasting blood glucose is 114 mg/dL. What is the most likely diagnosis?

ExplanationThis patient presents at a young age with hypertension that is difficult to control, raising the question of secondary causes of hypertension. The most likely diagnosis in this patient is primary hyperaldosteronism, also known as Conn syndrome. The patient has no physical features that suggest congenital adrenal hyperplasia or Cushing syndrome. In addition, there is no glucose intolerance as is commonly seen in Cushing syndrome. The lack of episodic symptoms and labile hypertension make pheochromocytoma unlikely. The findings of hypokalemia and metabolic alkalosis in the presence of difficult-to-control hypertension yield the likely diagnosis of Conn syndrome. Diagnosis of the disease can be difficult, but the preferred test is the plasma aldosterone/renin ratio. This test should be performed at 8:00 AM, and a ratio above 30 to 50 is diagnostic of primary hyperaldosteronism. Caution should be made in interpreting this test while the patient is on ACE inhibitor therapy because ACE inhibitors can falsely elevate plasma renin activity. However, a plasma renin level that is undetectable or an elevated aldosterone/renin ratio in the presence of ACE inhibitor therapy is highly suggestive of primary hyperaldosteronism. Selective adrenal vein renin sampling may be performed after the diagnosis to help determine if the process is unilateral or bilateral. Although fibromuscular dysplasia is a common secondary cause of hypertension in young females, the presence of hypokalemia and metabolic alkalosis should suggest Conn syndrome. Thus, magnetic resonance imaging of the renal arteries is unnecessary in this case. Measurement of 24-hour urine collection for potassium wasting and aldosterone secretion can be useful in the diagnosis of Conn syndrome. The measurement of metanephrines or cortisol is not indicated.