The 5 years old boy presented with convulsions and vomiting for 6 d and obtunded sensorium for 3 d. Examination revealed elevated blood pressure (BP) (236/132 mmHg, 95th\nP = 108/71), brisk deep tendon reflexes with extensor planters and eye examination consistent with hypertensive retinopathy. He was having feeble peripheral pulses and was hypovolemic. He also had hyponatremic, hypokalemic, metabolic alkalosis with normal creatinine and elevated renin and aldosterone (Table ). Ultrasonography (USG) showed a small left kidney (5.7 cm) with loss of cortico-medullary distinction and enlarged hyperechogenic right kidney (7.1 cm). Computed tomography angiography (Figure ) confirmed occlusion of left renal artery distal to the origin, along with duplication of the artery. Magnetic resonance imaging (MRI) brain showed posterior reversible encephalopathy syndrome (PRES).
The patient was a 12-month-old boy who was the first child of healthy\nnon-consanguineous Japanese parents. He had egg allergy requiring elimination. He\nwas delivered spontaneously at 40 weeks and 2 days of gestation. His birth weight\nwas 3084 g (+0.21 standard deviation (SD), 50–75th percentile in Japan), body length\nwas 50 cm (+0.48 SD, 50–75th percentile in Japan), and head circumference was\n33.0 cm (−0.27 SD, 25–50th percentile in Japan). Phototherapy was performed due to\njaundice at 1, 2, and 4 days of age. Poor weight gain was noticed during health\nexamination at 3–4 and 6–7 months. He had fever 4 days before admission. The next\nday after fever onset, he was taken to a local physician because of vomiting and\nreferred to our hospital. At 2, 3, and 5 days after fever onset, drip infusion\ntherapy was repeatedly performed at the outpatient service without dramatic\nimprovement. Hence, he was finally admitted to our hospital.\nOn admission, his height was 73 cm (−0.77 SD, 10–25th percentile in Japan), his body\nweight was 7.3 kg, which was 6% lower than the pre-illness weight 7.8 kg (−1.3 SD,\n3–10th percentile in Japan), body temperature, 37.0°C; heart rate, 124 bpm;\nrespiratory rate, 42/min; and systolic blood pressure, 124 mmHg (⩾95th\npercentile + 12 mmHg). It did not persist and spontaneously decreased and his\nsystolic blood pressure was around 90th percentile until the eighth hospital day\neven after correction of dehydration, as shown in . Facial skin showed pallor, and\nenophthalmos was present, indicating dehydration. Hematological values were as\nfollows: white blood cell count, 5600/µL; hemoglobin, 15.5 g/dL; and platelet,\n9.4 × 104/µL. Blood chemistry and serologic findings were as follows:\ntotal protein, 7.3 g/dL; albumin, 4.7 g/dL; total bilirubin, 2.0 mg/dL; urea\nnitrogen, 19.7 mg/dL; creatinine, 0.29 mg/dL; uric acid, 9.3 mg/dL; aspartate\naminotransferase, 69 U/L; alanine aminotransferase, 26 U/L; lactic dehydrogenase,\n767 U/L; creatine kinase, 117 U/L; sodium, 127 mEq/L; potassium, 3.3 mEq/L;\nchloride, 85.2 mEq/L; glucose, 55 mg/dL; and C-reactive protein, 0.09 mg/dL. Venous\nblood gas analysis showed the following: pH, 7.456; pCO2, 28.9 mmHg;\npO2, 39.7 mmHg; , 19.9 mmol/L; base excess, −2.6 mmol/L; anion gap, 18.8 mmol/L;\nand lactate, 2.6 mmol/L. Urinalysis revealed a 2+ test for urine protein, 2+ for\noccult blood, and 1+ for ketone, but negative for urine sugar. Urinary β-2\nmicroglobulin was 1086 µg/L (normal: ⩽250 µg/L); α-1 microglobulin, 10.6 µg/mL\n(normal: ⩽5 µg/mL); and N-acetyl-β-d-glucosaminidase\n(NAG), 13.2 U/L (normal: ⩽5 U/L). Fractional excretion of sodium (FENa) and\npotassium (FEK) were 3.8% and 27.9%, respectively. Ultrasonographic study of the\nkidneys showed a difference in long axis diameter, where right and left was 4.7 and\n6.7 cm, respectively. Echocardiography on 33th day of admission showed pulmonary\nhypertension, left ventricular hypertrophy, and cardiomegaly. Left ventricular mass\nindex (LVMI) was 112.5 g/m2 and left ventricular ejection fraction was\n85%.\nHypoglycemia was treated with intravenous 12 mL of 10% glucose. Fluid therapy with\nisotonic solution was performed. At 12 h after admission, the amount of drip\ninfusion was about 450 mL. His body temperature was 37.5°C; heart rate, 118 bpm; and\nrespiratory rate, 28 breath/min. Assessed by blood gas analysis sample, sodium and\npotassium levels decreased to 122.8 and 2.72 mEq/L, respectively. Urinary osmolality\nwas 327 mOsm/kg. To avoid further lowering of sodium level, syndrome of\ninappropriate secretion of antidiuretic hormone (SIADH) was taken into\nconsideration. Hence, fluid intake was restricted. Approximately 30 h later, sodium\nimproved to 135.7 mEq/L. Hypokalemia improved by 5.75 mEq/kg/day of potassium oral\nadministration. On the sixth hospital day, pre-illness weight was achieved. Until\nthe eighth hospital day, systolic blood pressure and urine volume were 100–116 mmHg\nand 278–1165 mL/day, respectively. On the ninth hospital day, it was revealed that\nhe had no ophthalmologic complication such as cataract or coloboma associated with\nrenal tubular dysfunction. Those were screened by an ophthalmologist using mydriatic\nagent. In the afternoon, his blood pressure suddenly elevated. Systolic and\ndiastolic pressures were 154–160 and 70–84 mmHg, respectively. Urine volume\nincreased to 2290 mL/day. To investigate electrolyte and endocrinological problems,\nrenin and aldosterone values were measured. Plasma renin activity (PRA) was\n66.6 ng/mL/h (normal: 0.2–3.9 ng/mL/h) and plasma aldosterone level was 1112 pg/mL\n(normal: 35.7–240.0 pg/mL) on the second day of hospitalization.\nAs shown in , the\ndiuretic renogram showed right kidney dysfunction. Contrast computed tomography did\nnot detect renal artery stenosis (), but selective angiography revealed right renal artery\nstenosis at 2/3 of the site from aorta to branch (); the stenosis ratio was 99%,\nindicating that it led to increased plasma renin and aldosterone levels and\nhypertension. Brain magnetic resonance imaging (MRI) and MR angiography showed no\nother vascular lesion. As shown in , continuous intravenous infusion of nicardipine and oral\nadministration of doxazosin were required to manage hypertension. We also added oral\nadministration of furosemide, spironolactone, and carvedilol for myocardial\nhypertrophy and tachycardia. He needed intravenous nicardipine up to 10.5 µg/kg/min.\nIt was finally switched to oral use.\nOn the 65th hospital day, percutaneous transluminal balloon angioplasty (PTA) for\nright renal artery was performed. After PTA, proteinuria disappeared on 84th\nhospital day. Increased PRA (19.3–320.3 ng/mL/h) and plasma aldosterone level\n(2188.8–4518.0 pg/mL) lasted up to 16 months of age. Hence, doses of\nantihypertensive drugs were gradually decreased. Intravenous nicardipine was stopped\non 88th hospital day (at the age of 15 months). At the age of 22 months, it was\nrevealed that PRA and plasma aldosterone level were within normal limits and there\nwas no right renal artery restenosis evaluated by angiography. At about 1 year and\n2 months post-catheter intervention (at the age of 2 years and 4 months), we finally\nstopped the prescription of all antihypertensive drugs. His blood pressure was\n110/60 mmHg; height, 89.2 cm (+0.28 SD, 50–75th percentile in Japan); and body\nweight, 13.9 kg (+1.23 SD, 75–90th percentile in Japan). At the age of 2 years and\n5 months, LVMI was 63.2 g/m2. At the age of 2 years and 8 months, his\nblood pressure was 100/50 mmHg (<90th percentile).