Renal System >
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

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