Hyponatraemia Flashcards
What are the initial and late symptoms of hyponatraemia?
Initial: anorexia, nausea, malaise
Late: confusion, headache, irritability, weakness, low GCS and seizures
What classes of drugs can induce hyponatraemia? (5)
- Thiazide diuretics
- PPIs
- SSRIs
- TCAs
- Anti-epileptics
What is the likely source of hyponatraemia in a dehydrated patient with a urine Na+ of <20mml?
GI losses e.g. vomiting and diarrhoea
What is the likely cause of hyponatraemia in a dehydrated patient with a urinary Na+ of >20mmol/L?
Na+ and water loss through the kidneys e.g. diuretic excess, renal failure, Addison’s
What could be the cause of hyponatraemia in a pt who isn’t dehydrated but is oedematous? (4)
Cardiac failure
Nephrotic syndrome
Liver cirrhosis
Renal failure
What is the likely diagnosis in a patient with a urinary Na+ >20mmol/L and urine osmolarity >500mosmol/kg?
SIADH
How is chronic asymptomatic hyponatraemia managed?
Fluid restriction but demeclocycline (ADH antagonist) may be required
How is acute symptomatic hyponatraemia or hyponatraemia due to dehydration managed?
Cautious rehydration with 0.9% saline by a maximum rate of 15mmol/L per day if chronic or 1mmol/L per hour if acute.
When would furosemide use be considered in the management for hyponatraemia?
When patient is euvolaemic or hypervolaemic to prevent fluid overload
What can rapid overcorrection of hyponatraemia cause? How does it present?
Osmotic demyelination syndrome - dysarthria, paresis, confusion, low GCS
What are the main causes of SIADH? (4)
- Malignancy - SCL carcinoma, pancreatic, prostate, thymus, lymphoma
- Chest disease - TB, pneumonia, aspergillosis
- Endocrine - hypothyroidism (not true SIADH)
- Drugs - opiates, psychotropics, SSRIs and cytotoxics
How is SIADH managed?
- Treat underlying cause
2. Salt +/- loop diuretic if severe
