Hyponatremia and signals the kidney to bring back sufficient solute-free water from the fluid in the kidney tubules to dilute the serum sodium back to normal, and this turns off the osmoreceptors in the hypothalamus. Also, thirst is stimulated. Normally, when mild hyponatremia begins to occur, that is, the serum sodium begins to fall below 135 mEq/L, there is no secretion of ADH, and the kidney stops returning water to the body from the renal tubule. Also, no thirst is experienced. These two act in concert to raise the serum sodium to the normal range. Hyponatremia occurs 1) when the hypothalamic-renal
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