A 35-year-old woman comes to the emergency department with headaches and recurrent epistaxis. She has been told that her blood pressure is high during employee health visits but has not followed up. The patient does not use tobacco or illicit drugs. There is no family history of hypertension. Blood pressure is 170/100 mm Hg in the right arm and 175/105 mm Hg in the left arm, pulse is 80/min, and respirations are 14/min. Examination shows no jugular venous distension, normal lung sounds, and an S4 heart sound. Left upper quadrant abdominal bruit is present. Abdominal imaging reveals a left kidney size of 8 cm and a right kidney size of 12 cm. If measured, which of the following is most likely present in this patient?

Question

Quizplus · Accepted Answer

This patient has headaches and recurrent epistaxis, which likely result from her severe, uncontrolled hypertension. In the setting of the unilateral abdominal bruit and renal size discrepancy, this presentation suggests renal artery stenosis (RAS). Most cases of RAS occur in older males with diffuse atherosclerosis; however, young women can develop RAS due to fibromuscular dysplasia. A lateralizing systolic-diastolic abdominal bruit is a highly specific examination finding. Decreased renal perfusion in the poststenotic kidney results in atrophy of the affected kidney. Low perfusion pressures lead to increased renin secretion by the juxtaglomerular cells of the affected kidney and activation of the renin-angiotensin-aldosterone system (RAAS). This results in secondary hyperaldosteronism. Although this increases blood flow to the stenotic kidney and improves affected kidney's glomerular filtration rate, it is maladaptive and results in sodium retention, vasoconstriction, and hypertension. renin-angiotensin-aldosterone system (RAAS) In contrast, the unaffected kidney is exposed to high systemic pressures, leading to suppression of local renin secretion and pressure natriuresis. Although measurement of renal vein renin levels can help diagnose RAS, it is neither sensitive nor specific and requires an invasive procedure to obtain measurements. Less invasive approaches (eg, renal ultrasound with Doppler) are used as first-line diagnostic techniques. (Choice A) Generalized hypoperfusion (eg, hemorrhage, severe dehydration) results in increased renin excretion from the bilateral kidneys, leading to high serum aldosterone levels. (Choice C) Volume expansion (eg, excessive infusion of normal saline) results in suppression of the RAAS. (Choice D) Primary hyperaldosteronism (Conn syndrome) results in hypertension and leads to elevated serum aldosterone levels with suppression of renin. However, it would not cause renal atrophy or an abdominal bruit. (Choice E) ACE inhibitors and angiotensin-receptor blockers inhibit the effects of angiotensin II and result in elevated levels of renin (due to loss of feedback inhibition from angiotensin II) with low levels of serum aldosterone. (Choice F) RAS affecting the right kidney results in high renin levels in the right kidney with suppression of renin in the left; however, this patient's left-sided abdominal bruit and atrophic kidney suggest that the RAS is affecting the left renal artery. Educational objective: Renal artery stenosis typically presents with uncontrolled hypertension. A lateralizing abdominal bruit is a highly specific examination finding; atrophy of the affected kidney may be seen on imaging. Hypoperfusion of the post-stenotic kidney results in increased local renin secretion, leading to activation of the renin-angiotensin-aldosterone system and secondary hyperaldosteronism. Renin secretion by the unaffected kidney is suppressed.

A 35-Year-Old Woman Comes to the Emergency Department with Headaches