기립성 단백뇨는 안정시에는 요단백이 검출되지 않고 환동시에만 검출되는 양성질환으로, 정확한 병인은 확립되어 있지 않으나 최근 그 원인으로써 nutcracker 현상을 보고한 바 있다. 대부분 방사선학적 검사를 통하여 진단하고 추적관찰 동안에 저절로 단백뇨의 소실을 보이나, 본 증례의 경우, 24시간 소변의 단백이 1.5 g/일 이상 검출되고 3년 이상 지속되어 신조직의 병변을 알고자 신생검을 실시하여 메산지움 증식성 병리소견을 보였기에 문헌고찰과 함께 보고하는 바이다.
Orthostatic or postural proteinuria is a benign condition characterized by the presence of protein in urine samples collected in the upright position during the day and its absence in the supine position. Recently, nutcracker phenomenon has been documented as the source of postural proteinuria. The nutcracker phenomenon refers to compression of the left renal vein between the aorta and superior mesenteric artery, resulting in elevation of pressure in the left renal vein, leading to congestion of the left kidney and occasionally to collateral veins formation. Entrapment of the left renal vein is a cause of left-sided gross hematuria, ureteral and peripelvic varices, unexplained left flank pain and variable degrees of orthostatic proteinuria. We report the case of a 14-year-old girl with orthostatic proteinuria, diagnosed as having nutcracker syndrome by doppler sonography and MR angiography. Because daily protein excretion was more than 1.5 grams over 3 years of follow up, we decided to perform a renal biopsy which revealed moderate mesangial cell proliferation in all glomeruli.
