Abstract: PO2543
Unusual Cause of Calcium Oxalate Nephropathy in a Renal Allograft
Session Information
- Transplant Complications: Glomerular Disease and Genetics
October 22, 2020 | Location: On-Demand
Abstract Time: 10:00 AM - 12:00 PM
Category: Trainee Case Report
- 1902 Transplantation: Clinical
Authors
- McCoy, JoBeth, Vanderbilt University Medical Center, Nashville, Tennessee, United States
- Langone, Anthony J., Vanderbilt University Medical Center, Nashville, Tennessee, United States
Introduction
Crystal nephropathy is a well-known cause of acute kidney injury that is often overlooked. We present a case of oxalate nephropathy in a renal allograft that led to a rare diagnosis.
Case Description
A 63-year-old female with a kidney transplant for end-stage kidney disease (ESKD) caused by acute interstitial nephritis (AIN) presented with acute kidney injury. Her creatinine on presentation was 2.2mg/ dL from her baseline of 1.0mg/dL and increased to around 3.0mg/dL despite hydration. It was decided that she would benefit from allograft biopsy. The biopsy was devoid of any rejection but did have many foci of calcium oxalate crystal deposition with tubular injury. She was planned for a 24-hour urine collection for stone evaluation that showed an elevated urine oxalate level,140mg. She changed her diet and the 24-hour urine collection was repeated in 3 months with no change. With the continued elevation, genetic testing was sent for primary hyperoxaluria which revealed that she has homozygote mutation in the AGXT gene, confirming that she has type 1 primary hyperoxaluria. Reevaluation of her biopsy diagnosing AIN before transplant was found to have interstitial multinuclear infiltrate with some crystallization consistent with oxalate nephropathy. Her particular mutation responds well to pyridoxine (vitamin B6) so she was started on 600mg per day. Since treatment, her creatinine has stabilized at 3.0mg/dL. Her 24-hour urine evaluation has shown improvement in urine oxalate to 79mg, a 43.5% reduction.
Discussion
Primary hyperoxaluria type 1 (PH 1) is described by recurrence in a renal allograft in only 10% of cases. Delay in the diagnosis is common and results in a significant number of patients who have end-stage kidney disease (ESKD) at initial presentation. The rapidity of progression is determined by the residual enzyme activity and response to pyridoxine(vitamin B6). The definitive cure for PH 1 is liver transplantation that carries significant mortality risk. Medical management includes large fluid intake of greater than 3L/day to decrease tubular fluid oxalate concentration, potassium citrate-citric acid to increase the solubility of calcium oxalate and prevent precipitation, avoidance of oxalate in diet, and high dose pyridoxine to promote the conversion of glyoxylate to glycine rather than to oxalate. A trial of 5mg/kg of pyridoxine is suggested in all PH 1 patients to see how they respond.