Diabetes Insipidus Flashcards
1
Q
What is diabetes insipidus (DI)? (2)
A
Passage of large volumes of dilute urine (> 3L/d) because of impaired water resorption by the kidneys
2
Q
What causes impaired water resorption by the kidneys? (2)
A
- Reduced ADH secretion from posterior pituitary
- Kidney not responding to ADH
3
Q
What is cranial/ central DI?
A
Reduced ADH secretion from posterior pituitary
4
Q
What is nephrogenic DI?
A
Kidney not responding to ADH
5
Q
What are the clinical presentations of DI? (3)
A
- Polyuria (can lead to dehydration, hypotension)
- Polydipsia
- Increased plasma osmolality (fatigue, nausea, poor concentration)
6
Q
How do you diagnose DI? (2)
A
- Blood osmolality: > 290 mOsm/kg
- Water deprivation test: urine osmolality low
7
Q
How do you differentiate between cranial and nephrogenic DI? (2)
A
Give desmopressin (ADH analogue)
- Urine osmolarity increases to 50% = cranial DI
- Urine osmolarity slightly increases = nephrogenic DI
8
Q
How do you treat cranial DI? (2)
A
Desmopressin
Hydration
9
Q
How do you treat nephrogenic DI? (2)
A
Bendroflumethiazide (thiazide diuretic)
NSAIDs
