In a study to detect extracellular fluid volume, 10 gm mannitol was injected by intravenous route and after waiting for adequate time for equilibration of levels, concentration was measured as 50 mg/100 ml. In this time, 10% mannitol was excreted. What is the calculated volume of ECF?
Correct Answer: 18 Litres
Description: Ans. b. 18 Litres (Ref. Ganong 24/e p2)Out of 10 gm mannitol, 10% was excreted.Hence, amount of mannitol distributed in ECF = 10-1= 9 gmGiven concentration of mannitol in ECF = 50 mg/100 mlVolume of ECF = Amount/Concentration = 9 g/50 mg x 100 ml = 18 LBody FluidsWater constitutes approximately 60% of total body weightQ.Of this 60%, 40% is present in cells in the form of intracellular fluid (ICF) and 20% is present outside the cells in the form of extracellular fluid (ECF)Q.20% of body weight water in ECF is divided into interstitial fluid (15% of body weight) and plasma (5% of body weight)Q.Body FluidsTotal Body Water (60% of body weight)QIntracellular fluid (ICF)Extracellular fluid (ECF)* 2/3rd of TBWQ (40% of body weight)* 1/3rd of TBW (20% of body weight)QECFPlasmaInterstitial fluid* 25% or 1/4th of ECF* 5% of body weightQ* 75% or 3/4th of ECF* 15% of body weightQMost of the fluids are calculated directly from dilution methods, except for ICF & interstitial fluids. Both of these are calculated indirectly by calculating other body fluids.ICF= Total body water volume - ECF volumeInterstitial fluid = ECF volume - Plasma volumeFluid volumeindicator usedTotal body water volume* Deuterium oxide: D20 (MC used)Q* Tritium oxideQ* AmlnopyrineQ* AntipyrineQExtracellular fluid volume* Inulin (most accurate)Q* Sucrose* Mannitol* Sodium thiosulphatePlasma volume* Evans blueQ* Serum albumin labeled with radioactive iodineQ (1-125)Red cell volume* Cr-51 labeled RBCQ
Category:
Physiology
Get More
Subject Mock Tests
Practice with over 200,000 questions from various medical subjects and improve your knowledge.
Attempt a mock test nowMock Exam
Take an exam with 100 random questions selected from all subjects to test your knowledge.
Coming SoonGet More
Subject Mock Tests
Try practicing mock tests with over 200,000 questions from various medical subjects.
Attempt a mock test now