<unk>  volume depletion The most common cause of hypovolemia is diarrhea or vomiting. The other causes are usually divided into renal and extrarenal causes. Renal causes include overuse of diuretics, or trauma or disease of the kidney. Extrarenal causes include bleeding, burns, and any causes of edema (e.g. congestive heart failure, liver failure).<unk>  volume depletion is divided into three types based on the blood sodium level: # Isonatremic (normal blood sodium levels) Example: a child with diarrhea, because both water and sodium are lost in diarrhea. # Hyponatremic (abnormally low blood sodium levels). Example: a child with diarrhea who has been given tap water to replete diarrheal losses. Overall there is more water than sodium in the body. The<unk>  volume is low because the water will move through a process called osmosis out of the vasculature into the cells (intracellularly). The danger is tissue swelling (edema) the most important being brain edema which in turn will cause more vomiting. # Hypernatremic (abnormally high blood sodium levels). Example: a child with diarrhea who has been given salty soup to drink, or insufficiently diluted infant formula. Overall there is more sodium than water. The water will move out of the cell toward the<unk>  compartment down the osmotic gradient. This can cause tissue breakage (in case of muscle breakage it is called rhabdomyolysis).<unk>  volume overload<unk>  volume overload can occur during surgery, if water rather than isotonic saline is used to wash the incision. It can also occur if there is inadequate urination, e.g. with certain kidney diseases.
Intravascular volume status
Renal physiology
Cardiac reserve
Renal blood flow
Blood volume
Pathophysiology of heart failure
Dialysis adequacy
Cardiovascular physiology