NPNs: Urea

catabolites of protein and nucleic acid metabolism

NPNs are (5)

Major waste product dietary protein and amino acid catabolism

Synthesized in the liver from Co2 and Ammonia from DEAMINATION OF AMINO ACID and excreted by kidney

First metabolite to increase in kidney disease

Good indicator of 1. Nitrogen status 2. State of hydration

Amount of dietary protein Kidney’s ability excrete urea Protein Metabolism Degree of hydration

Condition by which there is an INCREASED IN BLOOD UREA

Condition by which ALL NPNS INCREASED

Concentration is expressed only as the ___ content of urea

____ x BUN = Urea

____ x 0.467 = BUN

Reference Value for Urea

Laboratory Methods for Urea: Specimen Requirement

Laboratory Methods for Urea: Tubes to be avoided in BUN (Inactivates Urease)

Laboratory Methods for Urea: If delay testing, spx must be _____ to avoid bacteria utilization to urea

Laboratory Methods for Urea: Chemical Method (Direct) for Urea ; Nonspecific, Simple

Laboratory Methods for Urea: Fearson Reaction / Diacetyl Monoximide Method = Result

Laboratory Methods for Urea: Enzymatic Method (Indirect) (2)

Laboratory Methods for Urea: Hydrolysis of Urea by Urease; Ammonium + Nessler;s Reaction (HgI or KI and gum ghatti) =

Hydrolysis of Urea by Urease; Ammonium + Berthelot’s reaction (Alk. Hypochlorite, Na nitroprusside) =

Laboratory Methods for Urea: Specific, more expensive Uses GLUTAMATE DEHYDROGENASE Measures disappearance of NADH at 340 nm

Laboratory Methods for Urea: Conversion of ammonium to Urea causes increased in conductivity

Laboratory Methods for Urea: Reference Method