Isotonic crystalloids are commonly used for which indication?

• A. Resuscitation
• B. Reducing intracranial pressure
• C. Lowering blood pressure
• D. Administering chemotherapy

Answer: (A)

Isotonic crystalloids expand circulating volume to treat hypovolemia. They have osmolality close to plasma, so they stay mainly in the extracellular space and promptly increase intravascular volume, improving venous return and tissue perfusion. This makes them the standard initial fluid for resuscitation in shock or dehydration. They aren’t used to specifically reduce intracranial pressure (that role is filled by hypertonic/osmotic agents), nor are they a primary choice for lowering blood pressure or for chemotherapy administration, though they may be used for hydration in various contexts.