All of the following are used to measure ECF volume, except: (A) Sucrose, (B) Sodium chloride, (C) Inulin, (D) Heavy water
Answer is B. ECF is measured using inulin which is a polysaccharide. Other substances used are mannitol and sucrose. These substances cannot enter a cell but can freely cross the capillary membrane and thus distribute evenly in the ECF compaments. (REF: TEXTBOOK OF MEDICAL PHYSIOLOGY GEETHA N 2 EDITION, PAGE NO - 61)