Interstitial fluid volume can be determined by:
(A) Radioactive iodine and radiolabelled water (B) Radioactive water and radiolabelled albumin (C) Radioactive sodium and radioactive water (D) Radioactive sodium and radioactive labelled albumin
(D) Ans: D. Radioactive sodium and radioactive labelled albumin(Ref Ganong 25/e p3, 24/e p2; Guvton I p309, 310)Fluid volumeIndicator usedTotal body water volumeDeuterium oxide: D20 (MC used)degTritium oxidedeg, Aminopyrinedeg, AntipyrinedegExtracellular fluid volumeInulin (most accurate)degs22Na, 1251-iothalamate, thiosulfatedegPlasma volumeEvans bluedegSerum albumin labeled with radioactive iodinedeg (1-125)Intracellular fluid(Calculated as total body water - extracellular fluid volume)Blood volume"Cr-labeled RBCsdeg, or calculated as blood volume = plasma volume/ (1 - hematocrit)Interstitial fluid(Calculated as extracellular fluid volume - plasma volume)