A 67-year-old man is admitted to the hospital due to acute right-sided weakness. Medical history includes hypertension, hyperlipidemia, and coronary artery disease, for which the patient underwent placement of 2 stents in the left anterior descending artery. He also has intermittent claudication that limits exercise capacity. The patient's antihypertensive regimen includes chlorthalidone, amlodipine, and lisinopril, which he takes as prescribed. He is an ex-smoker with a 35-pack-year history. Blood pressure is 180/110 mm Hg and pulse is 80/min. Serum creatinine is 1.6 mg/dL. CT scan of the head reveals hemorrhage of the left basal ganglia, and renal ultrasound shows that the right kidney is 7 cm long and the left kidney is 11 cm long. Which of the following mechanisms most likely explains the renal morphology in this patient?

Question

A 67-year-old man is admitted to the hospital due to acute right-sided weakness.  Medical history includes hypertension, hyperlipidemia, and coronary artery disease, for which the patient underwent placement of 2 stents in the left anterior descending artery.  He also has intermittent claudication that limits exercise capacity.  The patient's antihypertensive regimen includes chlorthalidone, amlodipine, and lisinopril, which he takes as prescribed.  He is an ex-smoker with a 35-pack-year history.  Blood pressure is 180/110 mm Hg and pulse is 80/min.  Serum creatinine is 1.6 mg/dL.  CT scan of the head reveals hemorrhage of the left basal ganglia, and renal ultrasound shows that the right kidney is 7 cm long and the left kidney is 11 cm long.  Which of the following mechanisms most likely explains the renal morphology in this patient?

Quizplus · Accepted Answer

11ec160b_38e6_e4f9_9249_a3b4c8ee8b90_MD0001_00 This patient has an intraparenchymal hemorrhage in the setting of severe, refractory hypertension. He has coronary artery disease and peripheral vascular disease (claudication) with multiple risk factors (eg, smoking, hyperlipidemia) for diffuse atherosclerosis. The elevated serum creatinine and the renal ultrasound demonstrating a small (atrophic) right kidney suggest that the patient's refractory hypertension is most likely due to unilateral renal artery stenosis. The most common cause of renal artery stenosis is obstruction by atheromatous plaque at the origin of the renal artery, leading to unilateral renal ischemia. The ischemic kidney secretes high levels of renin, which activates the renin-angiotensin-aldosterone system and results in systemic hypertension that is often difficult to control despite aggressive antihypertensive therapy. Eventually, the stenosis may also cause renal atrophy due to oxygen and nutrient deprivation. On histologic examination, the atrophic kidney shows crowded glomeruli, tubulointerstitial atrophy and fibrosis, and often, focal inflammatory infiltrates. (Choice A) Congenital renal hypoplasia is a failure of the kidneys to develop to normal size. Involvement is unilateral in most cases. However, this condition does not cause secondary hypertension. (Choice B) Unilateral denervation of a kidney, either during or after development, is not known to have significant trophic effects (affecting kidney growth or morphology). (Choice C) The role of trophic hormones in renal development remains unclear. Still, a deficiency of such hormones would be expected to produce bilateral renal dysplasia. (Choice E) Aging is associated with loss of nephron mass as a result of variable degrees of arteriolosclerosis, focal glomerulosclerosis, and tubulointerstitial fibrosis. These processes produce symmetric, not unilateral, decrements in kidney size and functional capacity. Educational objective: Renal artery stenosis is most often due to atherosclerosis. It can cause severe, refractory hypertension due to activation of the renin-angiotensin-aldosterone system. Over time, renal atrophy may occur due to chronic oxygen and nutrient deprivation. Histologic examination may show crowded glomeruli, tubulointerstitial atrophy and fibrosis, and focal inflammatory infiltrates. __________ References: Renal artery stenosis. (http://www.ncbi.nlm.nih.gov/pubmed/25439331)

A 67-Year-Old Man Is Admitted to the Hospital Due to Acute