diabetes insipidus

Question 1

defined as?

Answer 1

passing large volumes of water per day

Question 2

what two reasons are there for causing this

Answer 2

reduced secretion of ADH or impaired response of the kidney to ADH

Question 3

what would cause a central (unable to secrete adequate ADH?)

Answer 3

idiopathic (most common) 
genetic 
sarcoidosis 
pituitary tumour 
trauma to stalk

Question 4

causes of nephrogenic DI?

Answer 4

genetic
CKD
Drugs: lithium
Low potassium/high calcium

Question 5

presentation ?

Answer 5

polydypsia
polyuria (extremely excessive, all consuming)
dehydration

Question 6

gold standard diagnosis?

Answer 6

water deprivation test

Question 7

what is the water deprivation test?

Answer 7

give water and determine whether body is able to concentrate urine

Question 8

how can you differentiate between central and nephrogenic diabetes insipidus?

Answer 8

give ADH and check urine concentration and osmolality. urine will become more concentrate in central but not nephrogenic

Question 9

treatment of central DI?

Answer 9

give ADH synthetic = desmopressin

Question 10

if it is nephrogenic - obviously desmopressin will be useless. what would you give?

Answer 10

thiazide diuretics which will generate hyponatraemia and drive water reabsorption