Severe Hypertension in a Female Adolescent with Severe Chronic Obstructive Unilateral Hydronephrosis

Introduction: Hypertension is rare in patients with a unilateral ureteral obstruction (UUO) due to a functional compensation from the contralateral kidney. We describe an adolescent who had severe hypertension and an incidental finding of a congenital UUO. We postulated the mechanisms of hypertension and highlighted the decision-making dilemma on therapeutic intervention. Case Description: A 15-year-old African American female was admitted for shortness of breath, pharyngitis, and fever. BMI was 29.3 kg/m2, T 102.7 F, HR 118/min, RR 26/min, and BP 158/101 mmHg. CT angiogram did not reveal pulmonary embolism. Instead, she had severe right-sided hydroureteronephrosis with extreme cortical thinning (Fig 1A). On renal US, right kidney measured 22.1 x 9.6 x 10.7 cm while left kidney was 11.4 x 6.0 x 6.0 cm. The washout times of the LK and RK on diuretic renogram were 7 (30%) and 46 (70%) minutes respectively (Fig 1B). Plasma renin activity, serum creatinine and aldosterone were normal. Her BP was controlled with labetalol and thereafter angiotensin-receptor blocker. A pediatric urologist contemplated a right-sided nephrectomy. Discussion: Studies showed elevation of plasma renin in hypertensive acute UUO but it is often normal in chronic UUO. Plausible mechanisms for intrarenal generation of renin in the latter may include renal ischemia, ureterorenal reflex [prostaglandins], and distension of renal capsule with its sympathetic innervation. Given the rapid control of the BP, and absence of a prior acute pyelonephritis, we recommend supportive care rather than nephrectomy.