The present invention provides a system for the measurement of a tissue hydration value in a subject comprising a microprocessor and a sensor system having a light source and a light detector. Light is projected from the light source towards the tissue of a subject. The light projected either passes through or off of the tissues of the subject and is then received by the light detector. The light detector transmits a measurement of light intensity received by the detector to the microprocessor. The microprocessor is programmed with a tissue hydration model that utilizes the measurement of light intensity to determine the tissue hydration value for the subject.
