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Abstract: FR-PO896

Oxalate Nephropathy Due to Enteric Hyperoxaluria in the Renal Allograft: A Case Series

Session Information

Category: Transplantation

  • 1802 Transplantation: Clinical

Authors

  • Firth, Christine, The Mayo Clinic Arizona, Scottsdale, Arizona, United States
  • Ryan, Margaret, The Mayo Clinic Arizona, Scottsdale, Arizona, United States
  • Keddis, Mira T., The Mayo Clinic Arizona, Scottsdale, Arizona, United States
Background

Secondary hyperoxaluria due to enteric causes is an underrecognized cause of renal allograft injury and loss. We present a single center case series of oxalate nephropathy in kidney transplant (KTx) patients due to enteric hyperoxaluria (EH).

Methods

Cases of oxalate nephropathy based on pathological description from 2008 to 2018 were ascertained. Cases of primary hyperoxaluria were excluded. Clinical risk factors for EH, serum and urine oxalate levels around the time of the biopsy, treatment, and allograft outcomes were analyzed.

Results

Fifteen cases of oxalate nephropathy were identified. Median follow-up was 3.0 years (range 0.4 to 8.6 years). Median time from transplant to allograft biopsy showing oxalate nephropathy was 104 days (range 14 days to 8.6 years). The most common pre-Tx risk factors for EH included short bowel syndrome (27%) and gastric bypass (13%). Post-Tx risk factors included chronic diarrhea (33%) and frequent antibiotic use (27%) with presumed altered gut flora. Median serum oxalate was 13.4 umol/L (range 2.7 to 37.5 [normal 0.4 to 3]) and median 24-hour urine oxalate was 97.7 mg/24 hours (range 40.5 to 121.2 [normal 9.7 to 40.5]). The predominant treatment was a low oxalate diet, increased oral fluids (93%), coupled by dietician counseling (87%) and calcium supplementation (93%). At last follow-up, 6 patients had GFR<45ml/min, 4 had GFR<30ml/min and 4 were on dialysis. [Table1]

Conclusion

Enteric causes of hyperoxaluria in KTx patients can be attributed to pre and post-transplant risk factors. Oxalate nephropathy due to EH in KTx patients is an important cause of allograft failure and warrants a standardized approach for early detection and treatment approach tailored for patients’ unique risk factors.