Which of the following solution is a colloid:September 2007

Ans. B: AlbuminThere are two types of fluids that are used for intravenous drips; crystalloids and colloids.Crystalloids are aqueous solutions of mineral salts or other water-soluble molecules.Colloids contain larger insoluble molecules, such as albumin; blood itself is a colloid.Colloids preserve a high colloid osmotic pressure in the blood, while, on the other hand, this parameter is decreased by crystalloids due to hemodilution.Another difference is that crystalloids generally are much cheaper than colloids.The most commonly used crystalloid fluid is normal saline, a solution of sodium chloride at 0.9% concentration, which is close to the concentration in the blood (isotonic).Ringer's lactate or Ringer's acetate is another isotonic solution often used for large-volume fluid replacement.A solution of dextrose 5% in water, sometimes called D5W, is often used instead if the patient is at risk for having low blood sugar or high sodium.