- Decreased renal responsiveness to ADH
- Results in production of inappropriately dilute urine
- Meds that decrease effect of ADH on kidney→ e.g. Lithium, clozapine, cisplatin
- Hypercalcemia (link below for more info)
- Infiltrative diseases affecting the kidney (e.g. sarcoid, amyloid, myeloma)
- Following resolution of urinary tract obstruction
- Persistent thirst, drinking large volumes of water, polyuria
- Degree of DI varies based on how impaired kidney responsiveness is to ADH
- Decompensation occurs If/when unable to drink enough free water to keep up with urine losses
- May ultimately develop hypovolemia, confusion, hypernatremia
- May have symptoms related to process causing hypercalcemia (if that's root cause)
- Tachycardia, hypotension, dry mucous membranes (if significant volume depletion)
- Altered mental status if significant hypernatremia
- + water deprivation test: continue to make large volumes of urine, with UOSM< Serum OSM despite no oral intake
- Low urine OSM, low specific gravity (ie persistently dilute urine)
- Elevated serum Osm and elevated serum sodium if can't keep up with urine losses of free water
- Situation does not correct w/administration of DDAVP