At first phases of renal damage, kidney would allow to pass giant proteins such as albumin whose size is of order of nm., surpassing the glomerular zone and therefore going to the Bowman's space. In this manner at the glomerular area proteins can form charge density that would give origin to spontaneous currents. In this paper equations corresponding to the Kirchhoff equation are derived. The usage of classical electrodynamics and the diffusion equation allows to derive the voltage as function of permittivity. This can be seen as an efficient biomarker. Therefore advanced technologies with capabilities for measuring micro and nano voltages in prospective implanted devices might to play a crucial role to anticipate the renal damage.