POS-188 UNUSUAL PRESENTATION OF PRIMARY HYPEROXALURIA TYPE 1 AS POSTPARTUM ACUTE KIDNEY INJURY

Abstract

Primary hyperoxaluria type 1 (PH1) is a rare autosomal recessive disease caused by a mutation in the AGXT gene, resulting in deficiency of the alanineglyoxylate:aminotransferase enzyme. Often, the first sign is multiple recurrent nephrolithiasis, usually developped in second or third decade of life. This leads to renal interstitial and tubular damage, fibrosis, and end-stage renal disease (ESRD). We report an original case of PH type 1 without nephrolithiasis with unusual presentation as postpartum acute renal injury. A 34-year-old Tunisian woman was admitted to our center at 8 weeks postpartum with renal failure. She had no history of kidney stones or urinary tract infections. She had a family history of renal failure in her cousin. Her family history was also notable for consanguinity, her parents were first cousins. It was her first pregnancy, renal function was normal and she was delivered at 38 weeks, by elective cesarean section for persistent bleeding from low-lying placenta. The patient was seen by Nephrologist 8 week postpartum. She reported persistent bilateral flank pain, epigastralgia, nausea and vomiting, without fever. Blood pressure was 170/100 mm Hg and she appeared euvolemic. She reported maintaining fluid intake of approximately 2 L/day. Urinalysis shows no proteinuria, no hematuria and urine culture was negative. Her serum creatinine was 13,28 mg/dL, renal clearance (MDRD)= 3.4 ml/min, urea was 34.6 mmol/l, blood count revealed an hypochromic microcytic anemia (hemoglobin:6,3 g/dl; VGM=76.3; TCMH=26.7). Kidney ultrasounds show increased parenchymal echogenicity with altered corticomedullary differentiation without renal calculi (Fig.1). Kidney biopsy revealed abundant (> 90/hpf) optically clear intratubular crystalline inclusions which were accompanied by diffuse acute tubular injury, moderately severe tubulointerstitial scarring, and patchy moderate chronic interstitial inflammation, consistent with a crystalline nephropathy (Fig.2). On genetic testing, she was found to be homozygous for I244T mutation in the P11L-containing alanine:glyoxylate aminotransferase missense mutation in the AGXT gene, consistent with PH1. The patient began intensive hemodialysis (4 h, three times a week) and she was referred for combined liver and kidney transplantation. We report an unusual presentation of PH type 1 as acute kidney injury in the postpartum period without nephrolithiasis. Nephrologist should be aware of such situation.