Methods of determining fructosamine levels in blood samples
First Claim
1. A method of determining the level of fructosamine in a blood sample or sample derived from blood wherein the level of fructosamine reflects an average serum glucose level in the sample over a period of time, said method comprising the steps of maintaining the sample at a controlled temperature below 5°
- C., controlling the pH of the sample to a value between 10 and 11, adding a colouring agent to the sample and after a first delay in time taking a first colour measurement at a predetermined wavelength and after a second delay in time taking a second colour measurement at the predetermined wavelength and determining the fructosamine level in said sample by comparing any resultant change between said first and second colour measurements with those of standard solutions wherein the colouring agent, timing of the delays wavelength and pH conditions selected such that any change of colour in the colouring agent between said first and second colour measurements is caused predominantly by glucose in the sample that is reacted or associated with an amine group of protein and has undergone a molecular re-arrangement to form fructosamine and not materially by any non-specific reducing substances which may be present in the sample.
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Accused Products
Abstract
The determination of fructosamine levels in at least part of a blood sample for use in detecting diabetes in patients or deciding treatment levels is effected by controlling the temperature and pH of the sample, adding a coloring agent such as a nitro-blue tetrazolium and after a first delay in time taking a first color measurement at a predetermined wavelength and after a second delay in time taking a second color measurement at the predetermined wavelength, then comparing any resultant change between the first and second color measurements with those of standard solutions, the selected timing delays, wavelength, coloring agent and pH conditions being such that any change of color in the coloring agent between the first and second color measurements is caused predominantly by the glucose in the sample that is reacted with an amine group of protein and has undergone a molecular rearrangement to form fructosamine and not materially by any non-specific reducing substance which may be present in the sample.
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Citations
17 Claims
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1. A method of determining the level of fructosamine in a blood sample or sample derived from blood wherein the level of fructosamine reflects an average serum glucose level in the sample over a period of time, said method comprising the steps of maintaining the sample at a controlled temperature below 5°
- C., controlling the pH of the sample to a value between 10 and 11, adding a colouring agent to the sample and after a first delay in time taking a first colour measurement at a predetermined wavelength and after a second delay in time taking a second colour measurement at the predetermined wavelength and determining the fructosamine level in said sample by comparing any resultant change between said first and second colour measurements with those of standard solutions wherein the colouring agent, timing of the delays wavelength and pH conditions selected such that any change of colour in the colouring agent between said first and second colour measurements is caused predominantly by glucose in the sample that is reacted or associated with an amine group of protein and has undergone a molecular re-arrangement to form fructosamine and not materially by any non-specific reducing substances which may be present in the sample.
- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method of detecting diabetes mellitus by determining the level of fructosamine in a blood sample, comprising the steps of taking a blood sample, maintaining the sample at a controlled temperature below 50°
- C., controlling the pH of the sample to a value between 10 and 11, adding a colouring agent to the sample and after a first delay in time taking a first colour measurement at a predetermined wavelength and after a second delay in time taking a second colour measurement at the predetermined wavelength, obtaining corrected readings utilizing said colour measurements and comparing the corrected readings with corrected readings of standards representative of known stages of diabetes mellitus, wherein the colouring agent, timing of the delays, wavelength and pH conditions are selected such that any change of colour in the colouring agent between said first and second colour measurements is caused predominantly by glucose in the sample that is reacted or associated with an amine group of protein and has undergone a molecular re-arrangement to form fructosamine and not materially by any non-specific reducing substances which may be present in the sample.
- View Dependent Claims (15, 16, 17)
Specification