Two commonly administered IV fluids in medical practice are crystalloids and colloids. Crystalloids are by far the most common, as they consist of water and small water-soluble electrolytes that are easily absorbed from the blood stream. They are indicated for fluid maintenance, fluid replacement and resuscitation. Colloids are comprised of larger solutes (most commonly protein) and can be in natural form (blood or plasma) or manufactured form (albumin). Because of the size of the molecules, the fluid is more likely to remain in the intravascular space and for that reason, colloids may be indicated over crystalloids for resuscitation in the context of severe hypovolemia to avoid resulting shock.