Specimen Name Result Units Range
Plasma Sodium 125 mmol/L (135-145)
Potassium 5.1 mmol/L (3.5-5.5)
Chloride 89 mmol/L (100-109)
Bicarbonate 3 mmol/L (22-32)
Glucose 55 mmol/L (3.8-5.5)
Urea 18.9 mmol/L (2.7-7.2)
Creatinine 300 μmol/L (60-110)

Young female patient, comatose.
Diabetic Ketoacidosis
  • Hyperglycaemia : therefore diabetic disorder
  • Corrected [Na+] ≈ 140 mmol/L
  • Metabolic acidosis : ↑ AG ≈ 38 mmol/L
    • ↑AG > ↓HCO3- (≈ 21)
    • ∴ minimal renal HCO3- loss
  • Pre-renal AKI : U/C ratio ≈ 63

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