A method for analyzing a sample using cavity ring-down spectroscopy, comprising desorbing a first part of a sample from a thermal desorption tube heated to a first desorption temperature to load the first part of the sample into a ring-down cavity; for each of a first set of wavelengths: generating, via at least one laser (24, 28), a laser beam at the wavelength directed into the ring-down cavity; extinguishing the laser beam entering the ring-down cavity; and registering light intensity decay data for light exiting the ring-down cavity via a light intensity sensor system; loading a second part of the sample desorbed from the thermal desorption tube heated to a second desorption temperature; for each of a second set of wavelengths: generating, via the at least one laser (24, 28), a laser beam at the wavelength directed into the ring-down cavity; extinguishing the laser beam entering the ring-down cavity; and registering light intensity decay data for light exiting the ring-down cavity via a light intensity sensor system. determining, via at least one processor (205, 624), a probability from the light intensity decay data using a predictive model that is at least partially based on the dataset of light intensity decay data for the first set of wavelengths and the second set of wavelengths that a subject from which the sample was received has a physiological condition or a degree of a physiological condition at least indirectly using a dataset of light intensity decay data for previously analyzed samples for which the presence or absence of the physiological condition or the degree of the physiological condition has been identified. desorbing a first part of a sample from a thermal desorption tube heated to a first desorption temperature to load the first part of the sample into a ring-down cavity; for each of a first set of wavelengths: generating, via at least one laser (24, 28), a laser beam at the wavelength directed into the ring-down cavity; extinguishing the laser beam entering the ring-down cavity; and registering light intensity decay data for light exiting the ring-down cavity via a light intensity sensor system; loading a second part of the sample desorbed from the thermal desorption tube heated to a second desorption temperature; generating, via at least one laser (24, 28), a laser beam at the wavelength directed into the ring-down cavity; extinguishing the laser beam entering the ring-down cavity; and registering light intensity decay data for light exiting the ring-down cavity via a light intensity sensor system; loading a second part of the sample desorbed from the thermal desorption tube heated to a second desorption temperature; for each of a second set of wavelengths: generating, via the at least one laser (24, 28), a laser beam at the wavelength directed into the ring-down cavity; extinguishing the laser beam entering the ring-down cavity; and registering light intensity decay data for light exiting the ring-down cavity via a light intensity sensor system. determining, via at least one processor (205, 624), a probability from the light intensity decay data using a predictive model that is at least partially based on the dataset of light intensity decay data for the first set of wavelengths and the second set of wavelengths that a subject from which the sample was received has a physiological condition or a degree of a physiological condition at least indirectly using a dataset of light intensity decay data for previously analyzed samples for which the presence or absence of the physiological condition or the degree of the physiological condition has been identified. generating, via the at least one laser (24, 28), a laser beam at the wavelength directed into the ring-down cavity; extinguishing the laser beam entering the ring-down cavity; and registering light intensity decay data for light exiting the ring-down cavity via a light intensity sensor system. determining, via at least one processor (205, 624), a probability from the light intensity decay data using a predictive model that is at least partially based on the dataset of light intensity decay data for the first set of wavelengths and the second set of wavelengths that a subject from which the sample was received has a physiological condition or a degree of a physiological condition at least indirectly using a dataset of light intensity decay data for previously analyzed samples for which the presence or absence of the physiological condition or the degree of the physiological condition has been identified.