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Kidney Week

Abstract: FR-PO587

Retinal Oxalosis: An Unusual Presentation of Hyperoxaluria

Session Information

Category: Genetic Diseases of the Kidneys

  • 1202 Genetic Diseases of the Kidneys: Non-Cystic

Authors

  • Maggio, Tyler, University of Iowa Hospitals and Clinics, Iowa City, Iowa, United States
  • Sambharia, Meenakshi, University of Iowa Hospitals and Clinics, Iowa City, Iowa, United States
Introduction

Hyperoxaluria can be primary due to inherited disorders of enzymatic defects in the glyoxylate pathway causing decreased oxalate metabolism, or secondary from increased intestinal absorption. Type 1 primary hyperoxaluria (PH) is typically diagnosed in infancy/childhood, leading to kidney failure by the fourth decade of life with more mild presentation in types 2 and 3. Retinal oxalosis is a rare finding, especially in adults. Herein we describe a case of suspected primary hyperoxaluria diagnosed late in life causing rapid decline in kidney function and vision loss.

Case Description

An 81-year-old woman with history of coronary artery disease, melanoma, hypertension, CKD stage 2 was referred to kidney clinic for rapid worsening of kidney function. History was pertinent for left nephrectomy at age 15 presumably from kidney stones/pyelonephritis. Kidney function began rapidly deteriorating 6-8 months prior to the referral with minimal proteinuria (random urine protein creatinine ratio of 0.22) and no hematuria. Kidney biopsy was performed which showed calcium oxalate crystal deposition. Except for 4-6 glasses of iced tea daily, no other risk factors could be identified. Despite dietary restriction of oxalate, her kidney function decline continued, warranting peritoneal dialysis (PD) initiation. Four months post PD initiation she developed sudden worsening of vision and was found to have oxalate retinopathy after extensive evaluation ruling out other causes. Primary hyperoxaluria was suspected and she was referred for genetic testing at the kidney genetics clinic at our institution.

Discussion

Dialysis patients are at high risk of systemic oxalosis due to poor oxalate removal by dialysis. Treatment for PH Type 1 includes combined liver and kidney transplant in those with kidney involvement. Other treatment options include high dose pyridoxine, oral citrate and hydration. Lumasiran -an RNA interference agent- has been approved for PH Type 1. In those with ESKD, daily dialysis/dialysis with high flux dialyzers has been attempted with limited benefit. Our patient refused to switch to hemodialysis. Genetic testing was performed, and results are pending. Despite aggressive treatment oxalate retinopathy is known to be irreversible. Hyperoxaluria is a rare cause of nephrolithiasis and kidney failure yet should remain on the differential in the setting of rapid decline of kidney function with no clear cause.