What type of fluid is plasma considered in fluid therapy?

• A. Crystalloid solution
• B. Endogenous colloid
• C. Exogenous colloid
• D. Isotonic solution

Answer: (B)

In fluid therapy, fluids are often understood by whether they contain large molecules that stay in the intravascular space (colloids) versus small solutes that rapidly equilibrate across membranes (crystalloids). Plasma fits into the colloid category because it contains proteins like albumin that are large enough to exert oncotic pressure and keep water inside blood vessels. Since plasma comes from the patient's own body, it is considered endogenous. So, plasma is best described as an endogenous colloid—the body’s own fluid rich in proteins that help maintain intravascular volume. Crystalloids are small-molecule solutions, exogenous colloids are externally prepared colloid products (not the body's own fluid), and isotonic refers to a solution’s osmolality rather than the fluid’s origin or type.