Hyponatraemia (in context of malignancy)

Question 1

What are the potential causes of malignancy associated hyponatraemia?

Answer 1

1. Anticancer therapy e.g. vinca alkaloids, platinums, alkylating agents

Question 2

What are the symptoms of hyponatraemia?

Answer 2

1. Confusion
2. Headache
3. Seizure
4. Low GCS

Question 2

How is acute (<48 hours) and symptomatic hyponatraemia managed?

Answer 2

If symptomatic and sodium <120 will need hypertonic saline (200ml 2.7%)

Discuss with ICU

Check at 6, 12, 24 and 4 hours, should not correct by >10mmol in 24 hours

Question 2

If urine osmolality low (<100)…

Answer 2

Consider primary polydipsia

Question 3

How is non-symptomatic hyponatraemia (>48 hours) managed?

Answer 3

Assess hydration satus:

If patient is hypovolaemic - 0.9% normal saline

Euvolaemic - check urinary and palsma osmolalities and sodium. Cortisol and TFTs

If patient hypervolaemic (overloaded) - treat underlying cause e.g. CCF, renal failure, liver failure

Question 4

If plasma osmolality >275 hypertonic hyponaraemia

Answer 4

Hyperglycaemia e.g. HHS

Question 5

Plasma osmolality <275 AND urine osmolality >100
Hypotonic hyponatraemia

Answer 5

If urinary sodium high then SIADH
If urinary sodium low likely to not be euvolaemic

Question 6

SIADH management

Answer 6

If patient is euvolaemic, normal kidney function, normal adrenal function and normal thyroid function

Urinary sodium >20
Urinary osmolality >100
Serum osmolality <275

Manage with fluid restriction and expert help to manage tolvaptan