Diabetes Insipidus Flashcards
1
Q
Causes of DI (4)
A
- head trauma, brain tumor, irradiation of pituitary gland
- infections of CNS (Meningitis, encephalitis, tb)
- tumors
- failure of renal tubules to response to ADH
2
Q
What happens in DI?
A
decreased ADH or kidney response to ADH: profound water loss
3
Q
two main s/s of DI
A
- polydipsia
- large volumes of dilute urine
4
Q
two types of DI
A
- neurogenic: ADH deficiency
- nephrogenic: kidneys insensitive to ADH
5
Q
DI Clinical manifestations (7)
A
- > 250 ml/hr of very dilute urine: hypotension, tachycardia
- specific gravity 1.001-1.005
- decreased skin turgor and dry mucus membranes
- thirst and polydipsia, weight loss
- urine: no abnormal levels of glucose or albumin
- onset insidious or abrupt
- hypernatremia, severe dehydration, hypovolemia
6
Q
How is DI tested?
A
fluid deprivation test
7
Q
What is the fluid deprivation test? (3)
A
- withholds fluids 8-12 hours or until 3-5% of body weight is lost
- weigh patient frequently during the test
- plasma and urine osmolality studies: beginning and end of test
8
Q
DI diagnostic findings (4)
A
- increased serum osmolality and increased sodium levels
- assess plasma ADH levels
- assess plasma and urine osmolality
- trial of desmopressin therapy and IV infusion of hypertonic saline (not for patients with Na > 150)
9
Q
DI lab indicators (5)
A
- increased Na
- increased serum osmolality
- increased UO
- decreased urine osmolality
- urine sodium not affected
10
Q
DI management (3)
A
- volume replacement: monitor fluid status for overload
- hormone replacement (desmopression)
- identify and correct underlying path
11
Q
How is desmopressin given? caution in which patients?
A
- given intranasally q 12-24 hours
- caution in patients with CAD (leads to increased BP)
12
Q
how is neurogenic DI treated
A
desmopression –> allows kidneys to conserve water
13
Q
how is nephrogenic DI treated
A
Na restriction, which decreased GFR and enhances fluid reabsorption
