Specimen Name Result Units Range
Plasma Sodium 124 mmol/L (135-145)
Potassium 5.9 mmol/L (3.5-5.5)
Chloride 92 mmol/L (100-109)
Bicarbonate 20 mmol/L (22-32)
Anion Gap 18 mmol/L (7-17)
Glucose 6.1 mmol/L (3.8-5.5)
Urea 17.9 mmol/L (2.7-7.2)
Creatinine 170 μmol/L (60-110)
Osmolality 264 mmol/kg (275-295)
Urate 0.36 mmol/L (0.20-0.40)
Phosphate 1.60 mmol/L (0.80-1.45)
Total Calcium 2.28 mmol/L (2.10-2.55)
Albumin 43 g/L (34-48)
Globulins 24 g/L (22-35)
Total Bilirubin 12 μmol/L (6-24)
GGT 14 U/L (< 60)
ALP 57 U/L (30-110)
AST 25 U/L (< 45)
LDH 164 U/L (110-230)

60yo male with weakness, lethargy & general malaise.
Addison's Disease

Plus, mild ↑AG acidosis 2° to AKI ± lactate.

Electrolyte changes:

  • Hyponatraemia > 90%
  • Hyperkalaemia > 70%
  • Hypo-osmolality
  • Hypoglycaemia
  • Mild uraemia
  • Mild metabolic acidosis 2° to AKI → normal or mildly raised AG

General Features:

  • Weakness / fatigue - 100%
  • Hyperpigmentation > 90%
  • Hypotension > 90%
  • Hypovolaemia
  • Vomiting, diarrhoea, abmoninal pain > 60%

Aetiology:

  1. Primary adrenal insufficiency
    • Autoimmune - Addison's disease
    • Surgical removal - e.g. breast Ca
    • Infection
      • TB
      • Over-whelming sepsis
      • Histoplasmosis, cryptococcus, coccidioidomycosis
      • Viral - esp. in AIDS
    • Haemorrhagic/coagulopathic necrosis
      • Waterhouse-Friderichsen syndrome
      • Pseudomonas, menningococcus (esp. children)
      • Peripartum
      • Anticoagulant Rx
    • Rare causes
      • bilateral metastatic Ca
      • amyloidosis
      • sarcoidosis
  2. Secondary adrenal insufficiency
    • Hypopituitary syndromes
    • Pituitary suppression
      • Exogenous steroids (*most common)
      • Steroid secreting tumours
  3. Interference with hormone synthesis
    • Congenital hypoplasia - C21, C11, C17
      • C21-hydroxylase - adrenal virulization & hypoaldosteronism
      • C11-hydroxylase - adrenal virulization & hypertension
    • Enzyme inhibitors
      • metyrapone, mitotane
      • aminoglutethamide
      • ketoconazole
    • Cytotoxics

Causes of hyponatraemia & hyperkalaemia (Na+:K+ ratio < 25:1):

  • Addison's - hypo-osmolar, mild uraemia
  • K+-sparing diuretics
  • DKA - hyper-osmolar, hyperglycaemia
  • Renal failure - esp. salt-losing nephritis, hypo-osmolar & uraemia
  • ACE Inhibitors (rarely) - **Entresto®