Ethylene glycol toxicity

Background

• Characteristics
  • Component of antifreeze
    • Fluoresces yellow/green under Wood's lamp (neither Sn nor Sp)
  • Sweet taste
  • Lethal dose = 1g/kg
    • Volume depends on percentage of ethylene glycol in solution, typically 0.6 g/mL
    • 60 kg patient lethal dose ~ 100 mL
• Parent compound causes inebriation; metabolite (glycolic acid) causes toxicity

Clinical Manifestations

1. Stage 1 - CNS
   1. 30min-12hr after ingestion
   2. Pt appears intoxicated (slurred speech, ataxia, stupor, seizure, coma)
2. Stage 2 - Cardiopulmonary
   1. 12-24hr after ingestion
   2. Most deaths occur during this stage
      1. Hypertension, tachycardia, CHF
      2. ARDS, pulmonary infiltrates
      3. Hypocalcemia (chelation by oxalate)
      4. Myositis & CK elevation
3. Stage 3 - Renal
   1. 24-72hr after ingestion
      1. Flank pain, CVAT
      2. Hematuria, proteinuria, calcium oxalate crystals (50%)

Diagnosis

1. Chemistry
   1. Anion gap acidosis
      1. Will not be present immediately after exposure (only metabolite causes acidosis)
   2. Renal failure
2. Serum Osm
   1. Osm gap
      1. Calculated serum osm - measured serum osm
         1. Calculated serum osm = 2Na + BUN/2.8 + glucose/18 + ethanol/4.2)
      2. Normal < 10
      3. >50 highly suggestive of toxic alcohol poisoning)
      4. Note: Cannot rule out toxic ingestion with a "normal" osmol gap
         1. Only parent alcohol is osmotically active
            1. Delayed presentation may mean that much of it is already metabolized
3. Glucose
4. Alcohol levels
5. UA
   1. Hematuria, proteinuria, pyuria
   2. Calcium oxalate crystals (late finding; only seen in 50%)
   3. Urinary fluorescence (may be seen 6 hours after ingestion)
6. Total CK
7. VBG
8. ECG
   1. QT prolongation ~ hypocalcemia
9. APAP/ASA levels

Treatment

1. ADH enzyme blockade
   1. Fomepizole
      1. Indications:
         1. Ethylene glycol level >20mg/dL
         2. Suspected significant ethylene glycol ingestion w/ ETOH level <100mg/dL
         3. Coma or AMS in pt w/ unclear history and osm gap >10
         4. Coma or AMS in pt w/ unclear history and unexplained met acidosis and ETOH level <100
      2. Dosing
         1. 15mg/kg IV over 30min; follow by 10mg/kg q12hr until level <20 or acidosis resolves
   2. Ethanol
      1. BAL of 100-150 completely saturates alcohol dehydrogenase
      2. IV: load 800mg/kg; then give 100mg/kg/hr
      3. Oral: 3-4 1-oz "shots" of 80-proof liquor); then give 1-2 "shots" per hour
2. Correction of metabolic acidosis with bicarbonate
   1. Bicarbonate 1-2mEq/kg IV bolus to attain pH = 7.45-7.50
      1. Follow by infusion of 150mEq/L in D5 @ 1.5-2 times maintenance fluid rate
   2. Monitor for worsening hypocalcemia
3. Dialysis
   1. Indications:
      1. Refractory metabolic acidosis (pH <7.25) w/ AG >30
      2. Renal insufficiency
      3. Deteriorating vital signs despite aggressive supportive care
      4. Electrolyte abnormalities refractory to conventional therapy
      5. Ethylene glycol level >50mg/dL (controversial)
4. Decrease oxalate production
   1. Thiamine 100mg IV q6hr x2d
   2. Pyridoxine 50mg q6hr x2d
   3. Magnesium 2gm IV x1

Source

• Rosen's
• Uptodate