Low Sodium Flashcards
What are the normal plasma sodium levels?
135-145
What are the symptoms of hyponatraemia?
Agitation
Nausea
Focal neurology
What can cause hyponatraemia?
Sodium loss
Sodium/water imbalance
What can cause sodium loss?
D+V Diuretics Renal failure Peritonitis Burns
What causes sodium/water imbalance?
Changes to ADH secretion Heart failure Kidney disease Liver disease Medication
What drugs can cause sodium/water imbalance?
Thiazide diuretics SSRIs PPIs ACEi Loop diuretics
How do approach a patient with low sodium?
Assess osmolality
Fluid status
What is osmolality?
The measure of the number of particles dissolved in a kilogram of fluid
What is the normal range of osmolality?
275-295 mmol/kg
What is osmolarity?
The measure of the number of particles dissolved in a litre of fluid
How is osmolarity calculated?
2Na + glucose + urea
What can cause hypovolaemic hyponatraemia?
GI losses
Excessive sweating
Fluid in third spaces
Cerebral salt-wasting syndrome
What does urine sodium >20mmol/L + hypovolaemia show?
Renal loss
What does urine sodium >20mmol/L + euvolaemia show?
SIADH
What does urine sodium >20mmol/L + hypervolaemia show?
Renal failure
