<Li> False hyponatremia (due to massive increases in blood triglyceride levels or extreme elevation of immunoglobulins as may occur in multiple myeloma) </Li> <Li> Hyponatremia with normal tonicity can occur with high blood sugar . </Li> <P> The causes of and treatments for hyponatremia can only be understood by having a grasp of the size of the body fluid compartments and subcompartments and their regulation; how under normal circumstances the body is able to maintain the sodium concentration within a narrow range (homeostasis of body fluid osmolality); conditions can cause that feedback system to malfunction (pathophysiology); and the consequences of the malfunction of that system on the size and solute concentration of the fluid compartments . </P> <P> There is a hypothalamic - renal feedback system which normally maintains the concentration of the serum sodium within a narrow range . This system operates as follows: in some of the cells of the hypothalamus, there are osmoreceptors which respond to an elevated serum sodium in body fluids by signalling the posterior pituitary gland to secrete antidiuretic hormone (ADH), (also called vasopressin). ADH then enters the bloodstream 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 . </P>

Hyponatremia can lead to which of the following problems