Urea nitrogen^post dialysis/pre dialysis:MRto:Pt:Ser/Plas:Qn
urea nitrogen^post dialysis/pre dialysis:mrto:pt:ser/plas:qn
Urea nitrogen^post dialysis/pre dialysis:Mass Ratio:To identify measures at a point in time:Serum/Plasma:Quantitative
urea nitrogen^post dialysis/pre dialysis:mass ratio:to identify measures at a point in time:serum/plasma:quantitative