urine electrolyte analysis urine sodium analysis 2013-11-13T11:19:45Z A method which assesses the amount, proportions or properties of sodium in urine, the fluid waste product excreted by the kidneys. Sodium, the chemical element with atomic number 11 that in its ionic form has lost one electron, forming a cation with a charge of +1, is the chief cation of extracellular body fluids. JSmith MMO:0000434 measurement_method_ontology urine Na+ analysis urine sodium ion analysis