Abstract: A method of controlling a wearable device including a signal generator, two stimulation electrodes, and two sensing electrodes to monitor a level of edema of a subject, includes generating, by the generator, a signal that causes a current to flow between the stimulation electrodes and measuring an impedance between the sensing electrodes disposed on a skin of the subject at an interval of time during a testing period, thereby providing impedance measurements, validating each impedance measurement against a model set of impedance measurements, eliminating a measurement from the impedance measurements if the measurement fails the validating, thereby providing a validated sub-set of impedance measurements, converting each of the validated sub-set of impedance measurements to an edema index, thereby providing edema indices, averaging the edema indices and generating an average edema index for the testing period, and generating an alert depending on the average edema index.