Patent ID: 8591865

Claim:
A system for measuring the fluorescence intensity of a reporter fluorescent molecule and a marker fluorescent molecule in a vascular system of a mammalian subject to determine glomerular filtration rate (GFR) of the kidney of the mammalian subject, the system comprising: a source of said reporter fluorescent molecule and said marker fluorescent molecule; a means for introducing said reporter fluorescent molecule and said marker fluorescent molecule into the vascular system of the mammalian subject; a means for measuring the fluorescence intensity of said reporter fluorescent molecule and said marker fluorescent molecule within the vascular system of the mammalian subject; a means for determining an intensity ratio of the fluorescence intensity of said measured reporter fluorescent molecule and marker fluorescent molecule within the vascular system of the mammalian subject, and a means for calculating glomerular filtration rate (GFR) of the mammalian subject according to the equation: G ⁢ ⁢ F ⁢ ⁢ R = V 1 ⁡ ( A 2 + B 2 ) A 2 / α + B 2 / β wherein V 1 is plasma volume; A 2 and B 2 are constants; α is a fast phase decay constant; and β is a slow phase decay constant; wherein the ratio of intensity R(t) of the reporter fluorescent molecule and the marker fluorescent molecule are calculated at predetermined intervals; and wherein the constants A 2 , B 2 , α and β are calculated by fitting the ratio of intensity data to the following equation: R ( t )= A 2 e αt +B 2 e −βt where R(t) is the ratio of intensity as a function of time; wherein said reporter molecule is filtered by the kidney of the mammalian subject, and said marker molecule is retained in the vascular system of the mammalian subject; and wherein said reporter molecule and said marker molecule are chemically stable in the vascular system during measurement of kidney function.