21 year old female

Chief Complaint

• “I tried to kill myself”
• Drank beer and then blue liquid from her bedroom
  

Past Medical History

• Bulimia
• Depression

Vital Signs

• 37C, HR 103 beats/min, BP 120/62, RR 16, O2 99% room air, AccuCheck 101

Labs

• Sodium - 140 mmol/L
• Potassium - 3.4 mmol/L
• Chloride - 109 mmol/L
• CO2 - 19 mmol/L
• Creatinine - 0.7 mg/dL
• Glucose - 92 mg/dL
• BUN - 12 mg/dL
• Anion gap - 12
  
• Ethanol level - 172 mg/dL
• ABG - pH 7.32
• Serum Osmolality - 471 mOsmol/kg

Calculations

• Calculated Serum Osmolality = 2 x Sodium + Glucose/18 + Urea/2.8 + Ethanol/4.6
• 140x2 + 92/18 + 12/2.8 + 172/4.6
• Calculated serum osmolality = 326.8
• Measured serum osmolality = 471
• Osmolar Gap
• 144

DDx of Elevated Osmolar Gap

• Methanol
• Ethylene Glycol
• Isopropyl Alcohol
• Ethanol
• Acetone
• Propylene Glycol
• DKA
• Lactic acidosis

Calculations

• Methanol level – 485 mg/dL
• Calculated Serum Osmolality = 2 x Na + Glucose/18 + Urea/2.8 + Ethanol/4.6 + Methanol/3.2
• 140x2 + 92/18 + 12/2.8 + 172/4.6 + 485/3.2
• Calculated serum osmolality = 477
• Measured serum osmolality = 471

Methanol

• Methanol metabolized to formaldehyde and then formic acid by the enzyme alcohol dehydrogenase
• Formic acid causes an anion gap metabolic acidosis
• Respiratory and circulatory collapse
• Dizzy, headache, N/V, abd pain, blurry vision - within 12-24 hours of ingestion
  
• Formic acid can also also be metabolized to formate
• Formate can inhibit cytochrome oxidase and poison mitochondria
• Damages retina – “snowfield vision” to blindness
• Damages basal ganglia (putamen) - Parkinson-like syndrome

Hemodialysis (https://umem.org/educational_pearls/2680/)

• Which Modality
• Intermittent HD clears toxin faster than continuous renal replacement therapies
• When to initiate HD
• Neurologic dysfunction: Coma, seizures, new vision deficits
• Metabolic acidosis: blood pH <7.15 or persistent metabolic acidosis despite adequate supportive measures & antidotes
• Serum anion gap higher than 24 mmol/L
• Serum methanol concentration:
• > 700 mg/L (21.8 mmol/L) if fomepizole therapy is given
• > 600 mg/L or 18.7 mmol/L if ethanol treatment is given
• > 500 mg/L or 15.6 mmol/L in the absence of an alcohol dehydrogenase blocker
• When to stop HD
• HD can be terminated when the methanol concentration is less than 200 mg/L or 6.2 mmol/L and a clinical improvement is observed

Ethylene glycol

• Antifreeze, metal cleaners
• Metabolized by ADH to glycoaldehyde and eventually by ALDH to oxalic acid
• Neuro
• Sz, muscle spasms, CN deficits
• Cardio-Pulm
• Tachy, Tachypnea (acidosis) ARDS, CHF
• HypoCa2+, prolonged QTc, Ventricular arrhythmias
• Renal
• Ca2+-oxalate crystals damage kidneys
  

Isopropanol

• Rubbing alcohol
  
• Rapid GI absorption (~30 minutes)
• Metabolized by ADH to acetone
  
• Increased osmolar gap without metabolic acidosis and ketonemia and/or ketonuria
• CNS depression, hemorrhagic gastritis
  

Alcohol	Acidosis	Ketosis	Osmolar Gap
Methanol	+	+	+
Ethylene Glycol	+	+	+
Isopropyl	-	+	+
Ethanol	-	+	+