A method for measuring and determining urea level in human blood by reverse iontophoresis comprising the following steps of: placing an anode electrode on skin, placing a container comprising a solution including urease and a cathode electrode on skin, applying electric current to the anode electrode and the cathode electrode so that an electrical circuit is established there between, whereby urea molecules migrate from blood into the container, determining the urea level in the blood by the changes in the pH of the urease solution.