Zoledronic Acid-Associated Fanconi Syndrome in Patients With Cancer

Area of Science:

• Nephrology
• Oncology
• Pharmacology

Background:

• Zoledronic acid (ZA) is an antiresorptive bisphosphonate used for osteoporosis, bone metastases, and hypercalcemia.
• Renal excretion of ZA necessitates caution in patients with reduced kidney function due to accumulation risk.
• Acute kidney injury (AKI) is a known, though uncommon, complication of intravenous bisphosphonates.

Observation:

• Four cancer patients developed Fanconi syndrome approximately one week after ZA treatment.
• Patients presented with AKI, metabolic acidosis, hypophosphatemia, hypokalemia, and renal tubular defects.
• The temporal relationship strongly suggests ZA as the causative agent for Fanconi syndrome.

Findings:

• Generalized proximal tubular dysfunction (Fanconi syndrome) was observed in all four patients post-ZA.
• Key findings included electrolyte imbalances and impaired renal tubular reabsorption.
• This presentation highlights a specific pattern of ZA-induced nephrotoxicity.

Implications:

• Nephrologists and oncologists must consider ZA as a potential cause of new-onset Fanconi syndrome.
• Prompt recognition and discontinuation of ZA are essential for patient management.
• Awareness of this complication can prevent further renal damage and guide treatment decisions.