Specimen Name Result Units Range
Plasma Sodium 133 mmol/L (135-145)
Potassium 9.4 mmol/L (3.5-5.5)
Chloride 102 mmol/L (100-109)
Bicarbonate 6 mmol/L (22-32)
Anion Gap 34 mmol/L (7-17)
Glucose 7.2 mmol/L (3.8-5.5)
Urea 11.0 mmol/L (2.7-7.2)
Creatinine 290 μmol/L (60-110)
Osmolality 365 mmol/kg (275-295)
Urate 0.54 mmol/L (0.20-0.40)
Phosphate 4.02 mmol/L (0.80-1.45)
Total Calcium 2.17 mmol/L (2.10-2.55)
Albumin 48 g/L (34-48)
Globulins 31 g/L (22-35)
Total Bilirubin 5 μmol/L (6-24)
Conj. Bilirubin 1 μmol/L (1-4)
GGT 50 U/L (< 60)
ALP 124 U/L (30-110)
AST 37 U/L (< 45)
LDH 372 U/L (110-230)
Cholesterol 7.7 mmol/L (3.5-5.5)
ABG pH 6.77 (7.36-7.44)
PaO2 149 mmHg (70-100)
PaCO2 49 mmHg (35-45)
HCO3- 7 mmol/L (21-26)

44yo male admitted unconscious via ED.

High O2 requirement: FiO2 > 0.8
Methanol Overdose
  • high osmolar gap: measured - calculated → (365-293) ≈ 72 mmol/L
  • methanol : 0.13%
  • severe metabolic acidosis (↑AG but << ↑OG) ∝
    • lactate = 2.1 mmol/L
    • AKI will add some acid anion, but rarely AG>24 in AKI alone
    • ↑↑AG ≈ 34, so another acid anion present → likely formate
  • marked {hyperkalaemia + hyperphosphataemia + LDH} ∝ cell lysis
  • ABG:
    • PO2 + 1.25*PCO2 > 200 → on supplemental O2
    • actual FiO2 ≈ 0.8 → large ↑↑ AaO2 gradient (>350 mmHg)
    • PCO2 should be ≤ 10 mmHg if able to compensate
      ∴ respiratory acidosis ∝ CNS depression ± vomit/aspiration

 

Metabolic Acidosis - Raised Anion Gap (>18)

  1. Increased intake
    • salicylates → salicylate, lactate, ketoacids
    • ethanol → acetoacetate, lactate
    • methanol → formate, lactate
    • paraldehyde → formate, acetate, lactate
    • xylitol, fructose, sorbitol → lactate
    • ethylene glycol → oxalate
    • NB : rationale for administration of ethanol for methanol toxicity is competition for alcohol dehydrogenase & ↓ production of formate
  2. Increased production
    • ketoacidosis - DKA, ketoacidosis, starvation
    • lactic acidosis (types A & B)
      • shock, sepsis, major trauma
      • drugs, toxins - phenformin, cyanide, salicylate
      • enzyme defects
      • vitamin deficiency
  3. Decreased excretion
    • renal failure with retention of SO4/PO4 acids