Hyponatraemia

• Severe (< 120 mmol/L):
  • Symptoms: headaches, lethargy, comatose, seizures
  • Causes – see below chart
    • Hypovolemic
    • Euvolemic
    • Hypervolemic
• Fluid status is vital. High ADH in hypovolaemia is a normal response. SIADH is only if euvolemic.
• Diagnosis of SIADH
  • Urine osmolarity > 150 mmol/kg
  • Urine sodium > 20 mmol/L
  • Serum osmolarity < 270 mmol/L

Check if real or pseudo: glucose, triglycerides, uraemia proteins