Hypernatremia

“Elevated levels of serum sodium concentration (>145mmol/L) causing hyperosmolar state“

Risk Factors

• Modifiable:
  • Poorly controlled diabetes
  • Fluid loss via vomiting or diarrhoea
  • Increased sodium diet
• Non-Modifiable:
  • Increasing age

Aetiology

• Diuretics eg loop diuretics
• Dehydration
• Diabetes insipidus

Pathophysiology

• Loop diuretics
  1. Inhibit Na reabsorption in nephrons
  2. Increased water clearance only while Na remains
• Diabetes insipidus
  1. Lack of ADH production
  2. Less water reabsorbed by kidney tubules
  3. Dilute urine production
  4. Greater Na concentration remaining
• Diarrhoea & vomiting
  1. Fluid loss without replacement

Clinical Presentation

• Polydipsia
• Decreased skin turgor
• Dry skin
• Lethargy
• Confusion

• Advanced cases:
  • Muscle twitching
  • Spasms

Investigations

• Bloods:
  • Serum electrolytes: sodium, potassium, chloride
  • Urea & Electrolytes
  • Creatinine
  • Blood Gas
• Imaging: n/a
• Special: n/a

Management

• Correcting fluid and sodium balance.
• Mild cases: increase fluid intake
• Severe cases: IV drip (dextrose 5%)

Complications

• Correcting sodium concentration too quickly = cerebral oedema risk