Sudden-onset hypertension leading to the diagnosis of unilateral hydronephrosis due to ureteropelvic junction obstruction.

We present a case of a 41-year-old female who developed hypertension over a three-month period and was subsequently diagnosed with ureteropelvic junction obstruction (UPJO). The patient came to our department with elevated blood pressure. Blood examinations revealed normal renal function, hypokalemia and increased renin-angiotensin system (RAS) activity, as indicated by elevated level of plasma renin activity and plasma aldosterone level. A computed tomography imaging further revealed dilation of the left renal pelvis, atrophy of the left kidney, and indications of obstruction at the junction between the renal pelvis and ureter. Surgical intervention in the form of a left pyeloplasty successfully resolved the unilateral hydronephrosis, corrected the elevated RAS activity, normalized the blood pressure, and ameliorated the hypokalemia. This case emphasizes that elevated blood pressure might be the sole clinical indication of hydronephrosis. It's crucial to consider hydronephrosis due to UPJO as a potential cause, especially when diagnosing hypertension associated with RAS hyperactivity in young adults. It also highlights the effectiveness of surgical intervention in treating hypertension in such scenarios.