Extrarenal fluid losses, such as those that occur with the losses of sodium-containing fluids as in protracted vomiting, severe diarrhea, or sequestration of fluids in a 3rd space (see table Composition of Body Fluids), can cause hyponatremia typically when losses are replaced by ingesting plain water or liquids low in sodium (see table Approximate Sodium Content) or by hypotonic IV fluid.