Ethylene glycol toxicity

Background

• Component of antifreeze
• Toxic dose = 0.2mL/kg
• Letal dose = 1.4mL/kg
• Sweet taste
• Fluoresces yellow/green under Wood's lamp

Pathophysiology

• Ethylene glycol + aldehyde dehydrogenase > oxalate + glycolic acid

Work-Up

• Chemistry
  • Anion gap acidosis
  • Renal failure
  • Osm gap
    • Calculated serum osm = 2Na + BUN/2.8 + glucose/18 + ethanol/4.2)
  • Serum Osm
• Glucose
• Ethanol level
• UA
  • Hematuria, proteinuria, pyuria
  • Calcium oxalate crystals (late finding, only seen in 50%)
  • Urinary fluorescence (may be seen 6 hours after ingestion)
• Total CK
• VBG
• ECG
  • QT prolongation ~ hypocalcemia

Clinical Manifestations

• Patients may die in any stage!

• Stage 1 - CNS
  • 30min to 12h
  • Pt appears intoxicated (slurred speech, ataxia, stupor, sz, coma)

• Stage 2 - Cardiopulmonary
  • 12- 24h
  • Hypertension, tachycardia, CHF
  • ARDS, pulmonary infiltrates
  • Hypocalcemia (chelation by oxalate)
  • Myositis & CK elevation

• Stage 3 - Renal
  • 24- 72h
  • Flank pain, CVAT
  • Hematuria, proteinuria, calcium oxalate crystals (50%)

• Stage 4 - Delayed CNS
  • 6-12days
  • Cranial neuropathy

Treatment

1. Correction of metabolic acidosis with bicarbonate

• Bicarbonate 1-2mEq/kg IV bolus to attain pH = 7.45-7.50
  • Follow by infusion of 150mEq/L in D5 @ 1.5-2 times maintenance fluid rate
• Monitor for worsening hypocalcemia

2. ADH enzyme blockade

• Fomepizole (4-MP)
  • 15mg/kg followed by 10mg/kg q12hr x 4 doses
• Ethyl alcohol

3. Removal of parent alcohol and metabolites via dialysis

• Indications (controversial):
  • Severe acidosis (pH <7.30)
  • Renal compromise
  • Electrolyte imbalanes unreponsive to conventional therapy
  • Anion gap > 20

4. Other

• Thiamine 100mg IV q6hr and Pyridoxine 50mg q6hr
  • Theoretically decreases oxalate production
• Replace Magnesium
• Hypercalcemia
  • Symptomatic - treat cautiously (avoid further precipitation)
  • Asymptomatic - do not treat

Source

Rosen's