Specimen Name Result Units Range
Plasma Sodium 123 mmol/L (135-145)
Potassium 7.8 mmol/L (3.5-5.5)
Chloride 106 mmol/L (100-109)
Bicarbonate 3 mmol/L (22-32)
Anion Gap 22 mmol/L (7-17)
Glucose 30 mmol/L (3.8-5.5)
Urea 16.0 mmol/L (2.7-7.2)
Creatinine 450 μmol/L (60-110)
Urine Sodium 91 mmol/L (> 20)
Creatinine 655 μmol/L

Unconscious 16yo female.

History of abdominal pain, followed by sudden collapse.
Diabetic Ketoacidosis

Corrected [Na+] ≈ 130 mmol/L:

  • therefore 'true' hyponatraemia, i.e. persistent after correction of BGL
  • 2° to water ingestion & urinary Na+-loss

Decrease in HCO3- >> rise in AG:

  • HCO3- loss in urine in addition to ketosis
  • will have persistent NAG acidosis after correction of ketosis
  • may consider HCO3- replacement

Females tend to have slower onset of DKA:

  • more time to replace losses with water
  • greater excretion/loss of HCO3-

Hyperosmolar Hyponatraemia:

  1. Glucose
    • DKA, HONC
    • 'Corrected' [Na+] ≈ [Na+]Pl + [BGL-10]/3
  2. Urea:
    • esp. salt-losing nephritis
    • high [K+], creatinine, urea
  3. Others:
    • mannitol
    • glycine port-TURP
    • glycerol, sorbitol, ethanol, methanol

Differential:

  • IVT arm sample - normal osmolality
  • salt-losing nephritis - normal BGL, no ketones