Sodium disorders Flashcards
What is hyponatraemia?
Low blood sodium
What can cause hyponatraemia?
Excessive loss of sodium through gut or kidney
Reduced intake
Increased water intake without extra sodium
What is osmolality?
Measure of overall number of solute particles in a fluid
How can serum osmolality be measured?
2 x serum [sodium] + [urea] + [glucose]
What can cause high osmolality while having hyponatraemia?
Hyperglycaemia
Alcohol
Mannitol - a drug
What is hypernatraemia?
High sodium
What can cause normal osmolality with hyponatraemia?
Pseudohyponatraemia (lipaemia/hyperproteinaemia)
How can you workout if hyponatraemia is caused by salt loss or by water overload?
Assess ECF volume clinically - best test is lying/standing blood pressure
What would a change in postural hypotension be indicative of with hyponatraemia?
Sodium depletion
What can cause high ECF volume?
Congestive cardiac failure
Liver failure
Nephrotic syndrome
What can cause salt loss with a low urine sodium?
Diarrhoea and vomiting
What can cause salt loss with high urine sodium?
Diuretics
Adrenal insufficiency - low aldosterone
Cerebral salt wasting syndrome
Salt wasting nephropathy
What is Cerebral salt wasting syndrome?
Salt loss after severe head injury
What is psychogenic polydipsia?
Someone drinks water compulsively
What are criteria for Syndrome of Inappropriate Antidiuretic Hormone? (finish this answer
Hyponatraemia with hypo-osmolality
Inappropriate urinary concentration (urine osmolality >100mmol/kg
Elevated urine sodium
