LAUSR

A 22-month-old girl with a history of polydipsia (more than 3 L/day), polyuria (more than 3 L/day), and weight loss (from 12 to 10.6 kg) that started 4 months ago, with an initial impression of Bartter syndrome, was transferred from another hospital. Laboratory blood tests performed at the previous hospital revealed metabolic alkalosis, hyponatremia, and hypokalemia with a high transtubular potassium gradient (TTKG). Her blood pressure was measured to be 90/60 mmHg initially. However, the blood pressure checked upon arrival at our hospital was as high as 190/120 mmHg. Her height and weight were 86 cm (50–75th percentile) and 11.07 kg (25–50th percentile), respectively. Dehydrated lips and a large palpable abdominal mass were found on physical examination. There was no family history of inherited kidney diseases or hypertension. Laboratory study results were as follows: serum sodium 131 mmol/L, potassium 2.9 mmol/L, chloride 92 mmol/L, osmolality 265 mOsm/kg, bicarbonate 28.4 mmol/L, blood pH 7.57, BUN 4 mg/dL, creatinine 0.23 mg/dL, and estimated glomerular filtration rate (eGFR) 154.25 mL/ min/1.73 m2. She had proteinuria (urine protein/creatinine ratio 3.4 mg/mg) without hematuria or glucosuria. Urine electrolyte analysis showed diluted urine with osmolarity 157 mOsm/kg, sodium 27 mmol/L, chloride 32 mmol/L, and a TTKG of 5. Hormone studies for malignant hypertension revealed elevated plasma renin and aldosterone levels (renin 37 ng/mL/h, aldosterone 182 ng/dL), normal vanillylmandelic acid (VMA) levels, and normal levels of plasma and urine catecholamines. Abdominal computed tomography (CT) showed a large mass on the left kidney, encasing the left renal artery (Fig. 1a). Left ventricular hypertrophy was detected by echocardiography. Biopsy of the kidney mass revealed Wilms tumor, and other imaging evaluations confirmed no evidence of metastasis. Several antihypertensive medications failed to control hypertension. Hyponatremia and hypokalemia were transiently improved with intravenous fluid and oral electrolyte supplementation. After left radical nephrectomy, blood pressure and electrolyte imbalance were normalized, and no further medication was necessary.