usually hypotonic and isovolemic (SIADH) or hypovolemic (CSW)

Syndrome of Inappropriate Antidiuretic Hormone Secretion

Water retention secondary to excess ADH secretion from neurohypophysis

Severe/acute SIADH signs: restlessness, irritability, confusion, seizure, coma

Treatment: fluid restriction, daily weights and lytes, avoid raising Na >10mEq/L/24hrs (risk of osmotic demyelination syndrome or central pontine demyelination)

Cerebral Salt Wasting Syndrome

Direct neural effect on renal tubular function

Hypovolemia due to Na+ loss in urine triggers ↑ ADH secretion (appropriate)

Treatment: fluid replacement and electrolyte correction

Diabetes Insipidus

deficiency of ADH; hyPERnatremia secondary to volume depletion

Fracture in/near the sella turcica may tear the stalk of the pituitary gland resulting in disruption of ADH secretion from the posterior pituitary

Signs: polyuria, excessive thirst, polydipsia

Treatment: DDAVP (analog of ADH)

Route DDAVP Dose
intranasal (10-40mcg daily as single dose or divided in 2-3 doses/day)
PO (0.05 BID initially, 0.1-1.2mg/day divided in 2-3 doses)
IM (1-4mcg once daily)
  • References

    Elovic E, Baerga E, Galang GF, Cuccurullo SJ, Reyna M, Malone RJ. Physical Medicine and Rehabilitation Board Review. 3rd ed. New York, NY: Demos Medical; 2015. Chapter 2, Traumatic Brain Injury. P.96-146.

    DDAVP tablets/nasal spray/injection (desmopressin) [prescribing information]. Parsippany, NJ: Ferring Pharmaceuticals; December 2014.