Neurological Disorders Q 139

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After a hypophysectomy, vasopressin is given IM for which of the following reasons?

  

     A. To treat growth failure.

     B. To prevent syndrome of inappropriate antidiuretic hormone (SIADH).

     C. To reduce cerebral edema and lower intracranial pressure.

     D. To replace antidiuretic hormone (ADH) normally secreted by the pituitary.

    

    

Correct Answer: D. To replace antidiuretic hormone (ADH) normally secreted by the pituitary.

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After hypophysectomy or removal of the pituitary gland, the body can’t synthesize ADH. Initial management includes oral fluid replacement. However, in the event of unresolved DI, therapy is stepped up, ranging from fluid replacement with 5% dextrose to the administration of synthetic ADH analog, desmopressin. Intranasal desmopressin is the drug of choice for chronic cases of DI.

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Option A: Somatropin or growth hormone, not Vasopressin is used to treat growth failure. Childhood-onset is associated with decreased growth of all skeletal structures leading to dwarfism. Adult-onset HGH deficiency is less easily diagnosed as it has no single identifying feature that is pathognomonic. Typically adults have decreased skeletal muscle and increased fat mass in visceral tissue as well as decreased bone density and remodeling, which leads to osteoporosis.

Option B: SIADH results from excessive ADH secretion. Syndrome of inappropriate antidiuretic hormone ADH release (SIADH) is a condition defined by the unsuppressed release of antidiuretic hormone (ADH) from the pituitary gland or non pituitary sources or it’s continued action on vasopressin receptors.

Option C: Mannitol or corticosteroids are used to decrease cerebral edema. Glucocorticoids have shown potential benefit in cerebral edema secondary to vasogenic edema but have limited utility in other forms of edema and should be avoided altogether in the face of trauma. Mannitol is the primary agent used at doses of 0.25 to 1 g/kg body weight and is thought to exert its greatest benefit by decreasing blood viscosity and to a lesser extent by decreasing blood volume.

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