[Acute renal failure caused by phenazopyridine].

Area of Science:

• Nephrology
• Clinical Toxicology

Background:

• Phenazopyridine is a widely used analgesic for urinary tract infections.
• Drug-induced acute kidney injury (AKI) is a significant clinical concern.

Observation:

• A 27-year-old woman presented with abdominal cramps, jaundice, and oliguria following Chinese food consumption.
• Initial investigations including liver function tests and imaging were normal, but serum creatinine and urea nitrogen levels significantly elevated.
• The patient's urine was intensely orange, and she later admitted to ingesting 2,000 mg of phenazopyridine during a mental health crisis.

Findings:

• The patient developed acute renal failure with marked azotemia, characterized by a disproportionate rise in creatinine relative to urea nitrogen.
• Oliguria resolved spontaneously within 48 hours, and renal function normalized within 14 days without the need for dialysis.
• Persistent orange discoloration of urine was a notable clinical sign throughout the illness.

Implications:

• This case highlights phenazopyridine overdose as a rare but serious cause of reversible acute kidney injury.
• Clinicians should consider phenazopyridine toxicity in patients presenting with unexplained AKI and orange-colored urine.
• The distinct clinical course underscores the importance of detailed patient history in diagnosing drug-induced nephrotoxicity.