Hypotonic hyponatremia dramatic increase the serum sodium concentration and place the patient at risk for so-called "central pontine myelinolysis" (CPM). That disorder is characterized by major neurologic damage, often of a permanent nature. Because of the risk of CPM, people with low volume hyponatremia may eventually require water infusion as well as volume replacement. Doing so lessens the chance of a too rapid increase of the serum sodium level as blood volume rises and ADH levels fall. In people who are volume depleted, i.e., their blood volume is too low, ADH secretion is increased, since volume depletion is a potent stimulus for
Serum sickness proteins to form immune complexes. These complexes precipitate, enter the walls of blood vessels, and activate the complement cascade, initiating an inflammatory response and consuming much of the available complement component 3 (C3). The result is a leukocytoclastic vasculitis. This results in hypocomplementemia, a low C3 level in serum. They can also cause more reactions resulting in typical symptoms of serum sickness. Serum sickness can be developed as a result of exposure to antibodies derived from animals. These sera or antitoxins are generally administered to prevent or treat an infection or envenomation. Some of the drugs associated with serum sickness