Specimen Name Result Units Range
Plasma Sodium 158 mmol/L (135-145)
Potassium 4.6 mmol/L (3.5-5.5)
Chloride 118 mmol/L (100-109)
Bicarbonate 33 mmol/L (22-32)
Glucose 43 mmol/L (3.8-5.5)
Urea 16.0 mmol/L (2.7-7.2)
Creatinine 200 μmol/L (60-110)
Osmolality 393 mmol/kg (275-295)
Urine Ketones 0 Dipstick (Nil)

Female 80yo found unconscious.
Hyperglycaemic, Hyperosmolar, Non-ketotic Coma
  • Hyperglycaemia → diabetic disorder
  • Not ketotic / acidotic, ∴ HONC
  • HCO3- unusually high?!
    • ? pre-existing alkalosis
    • ? vomiting
  • Corrected [Na+] ≈ 169 mmol/L
  • Table: Lab values DKA vs HHS/HONC

 

Pathogenesis

  1. insulin deficiency → hyperglycaemia, but enough to prevent ketosis
  2. impaired renal function → exaggerating ↑glucose and hyperosmolality
  3. fluid restriction ∝ impaired thirst mechanism CNS disease or sedatives
  4. osmolality ≥ 350 mosm/kg → coma
    • correlation of osmolality & coma difficult due to variable contribution of urea
    • if urea is excluded, then coma generally occurs > 320 mosmol/kg