Hypotonic solutions include 0.45 percent sodium chloride and 0.33 percent sodium chloride. A 5 percent solution of dextrose in water is an isotonic solution, but it behaves as a hypotonic solution in the body following dextrose absorption, so medical professionals may use it in an IV as a hypotonic solution.
A hypotonic solution contains a relatively low concentration of dissolved solutes, meaning it has a high concentration of water. Thus, when a patient receives a hypotonic solution, the concentration of water in the solution is higher than the concentration of water in the patient's cells. This results in water traveling out of the hypotonic solution and into the cells. As a result, hypotonic solutions work well for treating true dehydration, which occurs when the body is only lacking water but has not lost any electrolytes.
Aside from hypotonic solutions, there are two other categories of IV fluids that medical professionals administer to patients. Hypertonic solutions have high electrolyte concentrations and are useful for treating patients suffering from hyponatremia, a condition in which blood sodium levels are low. Examples of hypertonic solutions are 10 percent dextrose in water and 5 percent dextrose in 0.45 percent sodium chloride.
Isotonic solutions are the third category of IV fluids. A solution is classified as isotonic when it has the same concentration of dissolved solutes as its outside environment. Biologically, isotonic solutions replace lost fluids while increasing blood vessel volume.