Hyponatraemia

• What serum sodium level is classed as hyponatraemia?

  <135mmol/L
• Why is hyponatraemia life threatening?

  Cerebral fluid shifts associated with the reduction in serum sodium.
• Is the rate of change in sodium concentration just as important as sodium level?

  Yes
• What sodium level is classed as severe?

  <120mmol/L
• What sodium level is classed as mild/moderate?

  >120mmol/L but less than 135mmol/L
• Give 3 symptoms of hyponatraemia

  Confusion

  Decreased GCS

  Seizures
• What management needs to commence in severe hyponatraemia?

  Hypertonic saline

  ICU care with high level monitoring
• In mild/moderate hyponatraemia...

  Perform fluid status examination

  Increase diruesis if hypervolaemic

  Gentle normal saline if hypovolaemic

  Fluid restriction if euvolaemic
• What is the first line investigation for hyponatraemia?

  Urine/serum osmolality and urine sodium
• Which medication can cause hyponatraemia?

  Thiazide diuretics
• When would you suspect SIADH?

  Hyponatraemia

  Raised urine osmolality in the presence of low serum osmolality
• Hypovolaemic and urinary sodium >20mmol/L causes

  Renal loss

  Addisons

  Renal failure

  Diuretics

  Osmotic diuresis
• Hypovolaemic and urinary sodium <20mmol/L causes

  Loss elsewhere

  Diarrhoea

  Vomiting

  Fistulae

  Burns

  Small bowel obstruction

  Excessive sweating
• Euvolaemic and urine osmolality >300mOsm/kg cause?

  SIADH
• Euovolaemic and urine osmolality <300mOsm/kg causes

  Water intoxication

  Severe hypothyroidism

  Glucocorticoid insufficiency
• Hypervolaemic causes

  Nephrotic syndrome

  Cardiac failure

  Cirrhosis

  Renal failure