10g of inulin is injected IV and after equilibrium the concentration of inulin in plasma is 50mg/100ml.if 10% of the inulin is excreated,what is the ECF Volume?
A.1.8L[23%]
B.18L[63%]
C.2.4L[11%]
D.24L[3%]
The principle is dye dilution techniques aka principle of volume distribution.
The formula : (unknown volume)V= (Q-e)/c
where Q= known quantity of dye used,
e = Amt of dye metabolized /excreted
and c = concentration of dye.
Here inulin is a dye used to evaluate ecf volume. Q = 10g, e = 10%= 1 g,
c = 50mg/100ml = 500 mg/1000ml = 0.5g/L
V= (10 -1)/0.5 = 9/0.5 =18L