Unusual Presentation of Oxalate Nephropathy Causing Acute Kidney Injury A Case Report

Introduction

Oxalate nephropathy is a rare but serious condition characterized by kidney damage due to oxalate crystal deposition. This case report highlights an unusual presentation of acute kidney injury (AKI) due to hyperoxaluria, emphasizing its diagnostic and treatment challenges.

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Case Summary

A 68-year-old male with a history of diabetes mellitus (Type 2), hypertension, and chronic kidney disease (CKD) Stage III presented with worsening renal function. The patient had been using polyethylene glycol for chronic constipation over the past six months. Upon admission, his serum creatinine was elevated to 7.7 mg/dL from a baseline of 1.4 mg/dL. Laboratory findings indicated metabolic acidosis and hyperkalemia, necessitating urgent intervention.

Diagnostic Findings

• Urinalysis: No proteinuria, hematuria, or significant crystal presence.
• Renal Ultrasound: Normal-sized kidneys with borderline increased echogenicity and multiple small kidney stones.
• Renal Biopsy: Marked interstitial fibrosis, tubular atrophy, and calcium oxalate crystal deposition, confirming oxalate nephropathy.
• Serum Oxalate Levels: Elevated (20.4 µmol/L; normal <1.6 µmol/L).
• 24-hour Urine Oxalate: Within normal range, ruling out primary hyperoxaluria.

Pathophysiology & Discussion

Polyethylene glycol (PEG), commonly used as a laxative, has been hypothesized to be depolymerized by gut bacteria into ethylene glycol, which can be converted to oxalate. This mechanism may explain the oxalate overload in our patient, exacerbated by his underlying CKD.

Treatment & Outcome

The patient required urgent hemodialysis to reduce serum oxalate levels. Additional interventions included:

IV calcium gluconate and insulin-dextrose therapy for hyperkalemia
Sodium bicarbonate drip for metabolic acidosis
Discontinuation of polyethylene glycol to prevent further oxalate accumulation
Management of underlying CKD and bladder outlet obstruction

Following two weeks of hemodialysis, the patient’s condition stabilized, and he was discharged with ongoing outpatient dialysis monitoring.

Clinical Implications

This case underscores the importance of:

• Recognizing polyethylene glycol as a potential risk factor for secondary oxalate nephropathy.
• Early identification of AKI causes in CKD patients to prevent irreversible damage.
• Considering oxalate nephropathy in patients with unexplained AKI, particularly those using certain medications.

References & Further Reading

Read the full study at https://doi.org/10.29328/journal.jcn.1001063.
Explore more clinical research at Journal of Clinical Nephrology.

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