MEDizzy - During a routine physical examination, a 42-year-old woman

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Urinary System

During a routine physical examination, a 42-year-old woman is found to have an elevated blood pressure of 150/100 mm Hg. Workup reveals a small left kidney and a normal-sized right kidney. Laboratory examination reveals elevated serum renin levels. Further workup reveals that renal vein renin levels are increased on the left but decreased on the right. Which of the following is the most likely cause of this patient’s hypertension?

ExplanationA rare cause of hypertension is renal artery stenosis, which may occur secondary to either an atheromatous plaque at the orifice of the renal artery or fibromuscular dysplasia of the renal artery. The former is more common in elderly men, while the latter is more common in young women. The decrease in blood flow to the kidney with the renal artery obstruction (Goldblatt kidney) causes hyperplasia of the juxtaglomerular apparatus and increased renin production. This produces increased secretion of angiotensin and aldosterone, which leads to retention of sodium and water and produces hypertension. Increased levels of aldosterone also produce a hyperkalemic alkalosis. The kidney with stenosis of the renal artery becomes small and shrunken due to the effects of chronic ischemia, but the stenosis protects this kidney from the effects of the increased blood pressure. The other kidney, however, is not protected and may develop microscopic changes of benign nephrosclerosis (hyaline arteriolosclerosis).