QW52-September 2025

Question: Select each option to validate with explanations

Clinical Case Scenario

A 45-year-old man working as a ground cleaner for an international airline presents to the emergency department with altered mental status and oliguria. He has a history of chronic alcohol use and was found unconscious near a maintenance area with multiple empty containers of aircraft de-icing fluid. Laboratory investigations reveal a serum creatinine of 3.5 mg/dL, a high anion gap metabolic acidosis, and calcium oxalate crystals in the urine

figure 1. De-icing procedure of aircraft

Figure 2. De-icing fluid to remove ice from aircraft body

Question: What is the most appropriate initial treatment?

A. Hemodialysis

B. Intravenous sodium bicarbonate

C. Intravenous ethanol or fomepizole

D. Forced diuresis with furosemide

E. Intravenous calcium gluconate

Wrong Answer: Indicated if severe acidosis, renal failure, or high ethylene glycol levels—but not first-line unless antidote unavailable or delayed

Wrong Answer: May help acidosis but doesn’t stop toxic metabolism

Right Answer: C. Intravenous ethanol or fomepizole Explaination:

This scenario reflects ethylene glycol poisoning, likely due to occupational exposure to aircraft de-icing fluid, which contains high concentrations of ethylene glycol. The patient’s altered sensorium, acute kidney injury, and classic lab findings point to toxic ingestion.

Key Diagnostic Clues:
● Occupational exposure: Aircraft de-icing fluid is a known source of ethylene glycol
● Chronic alcohol use: May predispose to ingestion or confusion with ethanol
● Anion gap metabolic acidosis: Due to glycolic and oxalic acid accumulation
● Calcium oxalate crystals: Pathognomonic for ethylene glycol toxicity
● Elevated creatinine: Suggests oxalate nephropathy and acute tubular injury
________________________________________

Pathophysiology:
Ethylene glycol is metabolized by alcohol dehydrogenase (ADH) into toxic metabolites:
● Glycolic acid → causes metabolic acidosis
● Oxalic acid → binds calcium → forms calcium oxalate crystals → nephrotoxicity
________________________________________

Treatment Strategy:
The first-line treatment is to block ADH to prevent formation of toxic metabolites.
● Fomepizole is preferred: potent ADH inhibitor, fewer side effects
● Ethanol competes with ethylene glycol for ADH, but harder to titrate
● Both prevent further toxicity and allow unmetabolized ethylene glycol to be excreted
________________________________________

Clinical Pearls

● Always suspect toxic alcohols in unexplained anion gap acidosis
● Calcium oxalate crystals are pathognomonic for ethylene glycol
● Early antidote administration is life-saving
● Hemodialysis is adjunctive—not initial—unless severe toxicity

Wrong Answer: Ineffective and potentially harmful in AKI

Wrong Answer: Used for hypocalcemia or cardiac toxicity—not relevant here unless severe hypocalcemia is present

Name

This field is for validation purposes and should be left unchanged.