Specimen Name Result Units Range

Plasma Sodium 144 mmol/L (135-145)
Potassium 2.4 mmol/L (3.5-5.5)
Chloride 86 mmol/L (100-109)
Bicarbonate 43 mmol/L (22-32)
Anion Gap 18 mmol/L (7-17)
Glucose 8.5 mmol/L (3.8-5.5)
Urea 10.0 mmol/L (2.7-7.2)
Creatinine 110 μmol/L (60-110)
Osmolality 300 mmol/kg (275-295)

63yo male.

Smoker 45 pkt-years.

CXR: ? hilar mass (FILM)

Cushing's syndrome - Ectopic ACTH
  • non-pituitary ACTH ∝ malignancy
    (most commonly lung, pancreas, or thymus)
  • sole cortisol excess should have near-normal Cl-
    → marked HCO3- retention will result in reciprocal Cl- fall ??
  • tend to present as 'biochemically Cushingoid', without other clinical features
    - e.g. truncal obesity, striae, etc.

 

Hypokalaemic Metabolic Alkalosis
Diuretics (esp. loop agents) - low Na+, Cl- / high urea
Mineralocorticoid excess - normal-high Na+, Cl- / normal urea
Vomiting / Gastric outlet obs. - very low Cl- / low-normal Na+ / high urea
Diarrhoea / laxatives - low Cl- / normal Na+ / high urea
Post massive transfusion - citrate metabolism & acidosis correction