SIADH

Question 1

sources of excess ADH?

Answer 1

posterior pituitary, ectopic ADH small cell lung cancer

Question 2

SIADH results in?

Answer 2

euvolaemic hyponatraemia

Question 3

what is the urine like?

Answer 3

high urine osmolality and high urine sodium

Question 4

presentation of SIADH?

Answer 4

asymptomatic
headaches
fatigue
muscle aches and cramps
confusion
sever hyponatraemia- seizures reduced consciousness

Question 5

what can cause SIADH?

Answer 5

SSRI
Infection: atypical pneumonia lung abscess
After op
Dont forget small cell lung cancer
HIV

Question 6

diagnosis of SIADH?

Answer 6

clinical features:
euvolaemia
hyponatraemia
low serum osmolality
high urine sodium
high urine osmolality

Question 7

other causes of hyponatraemia?

Answer 7

adrenal insufficiency
diarrhoea, vomiting burns excessive sweating
chronic kidney disease/ AKI, no heart failure liver disease excessive water intake
primary poldipsia

Question 8

primary polydipsia?

Answer 8

euvolaemic hyponatraemia, low urine osmolality and sodium

Question 9

management of SIADH?

Answer 9

admit if sodium under 125 or symptomatic
treat underlying cause
fluid restriction
vasopressin receptor antagonist (tolvaptan)/demeclocyclune

Question 10

sodium concentration should not change more than?

Answer 10

10mmol’L in 24 hours

Question 11

fluid restriction only allows?

Answer 11

750- to 1l a day

Question 12

osmotic demyelination syndrome/central pontine myelinolysis?

Answer 12

blood sodium is low causing water to move into brain tissue across BBB, which will cause brain to swell. it then reduces its solutes to prevent oedmatous. however if you rapidly replace sodium in blood water will shift out.

Question 13

2 phase symptoms?

Answer 13

1st- electrolyte imbalance, encephalopathic confusedm headache, vomitng seizures

2nd- demyelination of neurons (pons) spastic quadriparesis, pseudobulbar palsy, cognitive and behavioural changes.