title: Determination of serum urea by isotope dilution mass spectrometry as a candidate definitive method.
mesh_terms: D006801:Humans; D007201:Indicator Dilution Techniques; D013058:Mass Spectrometry / Q000379:methods; D010103:Oxygen Isotopes; D014508:Urea / Q000097:blood*
chemical_list: D010103:Oxygen Isotopes; D014508:Urea