Hyponatraemia Flashcards
What are the causes of pseudohyponatraemia? What will the serum osmolality be?
Hyperglycaemia
Mannitol
Hyperlipidaemia
TURP
Serum osmolality will be high or normal
What are the causes of hypervolaemic hyponatraemia?
CHF
Liver cirrhosis
Nephrotic syndrome
Chronic renal failure
Hypothyroidism
What are the causes of euvolaemic hyponatraemia?
SIADH
Beer potomania
What are the causes of hypovolaemic hypoernatraemia?
Diuretics
Vomiting / diarrhoea
Hypoaldosteronism
Sweating, burns, pancreatitis
What are the clinical features of hyponatraemia?
Headache, lethargy, N+V, dizziness, confusion, muscle cramps
Late signs - seizures, coma and respiratory
What is the management of hypovolaemic hyponatraemia?
IV fluids (saline, isotonic)
What is the treatment for euvolaemic hyponatraemia?
Fluid restriction 500-1L/day
Consider - demeclocycline and vaptans
What is the treatment for hypervolaemic hyponatraemia?
Fluid restriction 500-1L/day
Consider loop diuretics
Consider vaptans
What is the mechanism of vasopressin / ADH receptor antagonists? What patient groups is this medication avoided in?
Acts on V2 receptors - leads to selective water diuresis
Avoided in hypovolaemic patients
They are hepatotoxic in patients with underlying liver disease
What is the main complication of hyponatraemic treatment?
Osmotic demyelination syndrome
What is osmotic demyelination syndrome / central pontine myelinolysis?
Thought to occur secondary to astrocyte and oligodendrocyte apoptosis from rapid hyponatraemic correction
What are the complications of osmotic demyelination syndrome?
Dysarthria, dysphagia, paraparesis, quadriparesis, seizures, confusion, coma (usually irreversible)
Locked in syndrome can occur
