Diabetes Insipidus/ SiADH Flashcards
What causes DI?
Lack of or resistance to ADH
Symptoms of DI
Polyuria
Polydipsia
Hypernatraemia
No glycosuria
How do you investigate DI?
Water deprivation test
Urine volume per day
U & E
Ca++
How do you conduct a water deprivation test?
No water for 8 hours and measure urine osmoliality, then 8 hours after desmopressin (artificial ADH) given
What would the difference between cranial and renal DI b?
Cranial- low osmolality before ADH, high after
Renal- both low
What are the causes of cranial DI/
Idiopathic Tumours Infection/TB/meningitis Vascular- aneurysm, infarct Inflammatory- sarcoid or Langerhans Genetic
What are causes of nephrogenic DI
DM Lithium Tetracyclines CKD Post obstructive uropathy HYPERCALCAEMIA HYPOKALAEMIA AMyloid Genetic AQP2 defect
What is pathophysiology of cranial DI?
Hypothalamus doesnt produce ADH
What is pathophysiology of renal DI?
Resistance to ADH in collecting ducts
Management of DI
Treat cause
If congenital treat with high dose Vasopressin/Bendroflumethiazide (close monitoring needed)
What is SIADH?
Inappropirately high ADH
What are the causes of SiADH?
CNS- posterior pituitary issue, post-op, meningitis, head injury, abscess, encephalitis
Tumours- LUNG CARCINOMA (SCLC), Lyphoma, leukaemia, thymoma, sarcoma
Resp- pneumonia, TB, Asthma, penumothorax, ventilation, emphysema
Drugs- Carbamazepine, Thiazides, Cytotoxics, Desmopressin, Vasopressin, Oxytocin, SSRIs, PPIs
What electrolyte imbalance is seen in SiADH?
HYPONATRAEMIA,
Dilutional due to water retention
Symptoms of SiADH?
Headache Confusion Fatigue Muscle cramps LOC and seizures if severe
How do you diagnose SiADH?
Diagnosis of exlusion
