Diabetes Insipidus Flashcards
what is diabetes insipidus
lack of ADH or lack of response to ADH - prevents kidneys from being able to concentrate urine
symptoms of diabetes insipidus
polyuria (large amounts of urine)
polydipsia (excessive thirst)
how can diabetes insipidus be classified
nephrogenic
cranial
what is nephrogenic diabetes insipidus
collecting ducts of the kidney do not respond to ADH
what is cranial diabetes insipidus
decreased secretion of ADH from posterior pituitary
nephrogenic causes
Lithium Intrinsic kidney disease Inherited Hypokalaemia Hypercalcaemia
cranial causes
head injury
brain tumours
infections - meningitis
neurosurgery
what is serum and urine osmolality like in diabetes insipidus
high serum osmolality
low urine osmolality
what are sodium levels like in diabetes insipidus
hypernatraemia
investigation for diabetes insipidus
water deprivation test
how is water deprivation test carried out
no fluids for 8 hours - urine osmolality measured
desmopressin given
8 hours later urine osmolality is remeasured
if urine osmolality fails to increase after desmopressin is given, what is the diagnosis?
nephrogenic diabetes insipidus
- kidneys unable to respond to ADH
if urine osmolality increases after desmopressin is given, what is the diagnosis?
cranial diabetes insipidus
treatment of cranial diabetes insipidus
desmopressin
treatment of nephrogenic diabetes insipidus
thiazide diuretic
