Unraveling a Case of Oxalate Nephropathy: A Complex Presentation

Introduction: Hyperoxaluria, a rare condition, elevates calcium oxalate levels in the body, leading to deposition in various organs, particularly the kidneys. This can result in progressive renal function decline or kidney failure, known as oxalate nephropathy. Primary hyperoxaluria, a rare inborn error in glyoxylate metabolism, involves excessive oxalate production. Secondary hyperoxaluria is associated with either increased intake of oxalate rich food or increased absorption of oxalate from the gut in patient who have undergone intestinal surgeries, including gastric bypass. We will present a case of AKI associated with oxalate nephropathy in a patient with a history of uric acid stones Case Description: Patient, a 62-year-old female with longstanding type 2 diabetes mellitus, hypertension, asthma, morbid obesity, and obstructive sleep apnea managed with CPAP at home, has a history of surgical interventions including hysterectomy, cholecystectomy, and gastric bypass surgery in 2015. She experiences intermittent diarrhea managed by gastroenterologists. Previous nephrolithiasis episodes led to extracorporeal shockwave lithotripsy in 2012 and percutaneous nephrolithotomy in 2013 for left staghorn stones. Stone analysis revealed 100% uric acid composition. Multiple other episodes in 2014 were resolved via extracorporeal shockwave lithotripsy and fluoroscopic imaging. She has been followed by a nephrologist for gradual kidney function decline. In 2023, she presented with severe fatigue, weakness, and mild respiratory distress, found to have acute kidney injury (AKI) superimposed on chronic kidney disease. Initial labs showed elevated BUN, creatinine, and proteinuria. Kidney biopsy revealed oxalate nephropathy and diabetic glomerulopathy with interstitial fibrosis. Serum oxalate was markedly elevated at 52. She required hemodialysis and blood transfusions followed by placement of a Permcath for outpatient hemodialysis. The patient was discharged stable to continue care as an outpatient Discussion: This case sheds light on the persistent challenges of diagnosing and managing oxalate nephropathy in a rapidly progressive kidney failure in a patient with a complex medical history. It important to keep this entity in mind, especially in patients who are likely to develop secondary hyperoxaluria even though they may have had a different category of kidney stones in the past prior to their gastric bypass surgery