Patent ID: 8622920

Claim:
A method of quantitatively evaluating a liver function and/or a degree of liver injury in a subject, the method comprising: providing solution samples of isotope-labeled methacetin or a salt or a derivative thereof wherein the solution samples are produced in a process comprising: mixing, in a pre-determined amount of water, a pre-determined amount of isotope-labeled methacetin or the salt or the derivative thereof, to produce a solution; analyzing the solution to measure an amount of the methacetin or the salt or the derivative thereof dissolved in the solution; and providing for administration solution samples wherein, according to the analysis of the solution, at least 90% of the pre-determined amount of methacetin, or the salt or the derivative thereof, is dissolved in the solution; administering the analyzed solution sample to a subject in need thereof; following the administering, measuring a change in isotope ratio of a metabolic product of the isotope-labeled methacetin, or the salt or the derivative thereof, in the subject's breath using a breath sensor adapted to monitor the metabolic product of the isotope-labeled methacetin or the salt or the derivative thereof; and quantitatively evaluating the liver function and/or the degree of liver injury based on the measured change in the isotope ratio.