Diabetes insipidus Flashcards
What is it?
Large amounts of dilute urine are produced = extreme thirst
Types
Cranial
Nephrogenic
Cranial
Hypothalamus does not make enough ADH
Treatment:
- Vasopressin
- Desmopressin
Nephrogenic
Kidneys do not respond to ADH
Treatment:
- Diuretics (paradoxical effect)
Desmopressin
More potent analogue of vasopressin
Longer duration of action
No vasoconstrictor effects
Desmopressin - uses
Diabetes insipidus
Nocturnal enuresis
Desmopressin - Side effects
Hyponatraemic convulsions
Desmopressin - how to take
Limit fluid intake 1 hour before dose and until 8 hours after
Desmopressin - Common side effects
Fluid retention
Hyponatraemia on administration without restricting fluid intake
- More severe cases = convulsions
Headache
Stomach pain
N + V
Hyponatraemic convulsions
Increased risk when taking for nocturnal enuresis
Minimised by:
- Avoid fluid overload
- Stop medication during an episode of diarrhoea or vomiting (until fluid balance normal)
- Keep to recommended doses
- Avoid concomitant use of drugs which increase vasopressin secretion
Elderly
Increased risk of hyponatraemic convulsions
Measure baseline Na
Monitor regularly; discontinue if levels fall below baseline
Drugs which increase vasopressin secretion
- Paracetamol
- Nicotine
- TCAs
Pregnancy
Small oxytocic effect in 3rd trimester
Increased risk of pre-eclampsia
Desmopressin - more info
Used in the differential diagnosis - failure to respond indicates nephrogenic diabetes insipidus
Thiazide diuretics
Pituitary and nephrogenic diabtes may benefit
