NPNs: Urea Flashcards
catabolites of protein and nucleic acid metabolism
Nonprotein Nitrogen
NPNs are (5)
Urea
Ammonia
Creatinine
Creatine
Uric Acid
Major waste product dietary protein and amino acid catabolism
Urea
Synthesized in the liver from Co2 and Ammonia from DEAMINATION OF AMINO ACID and excreted by kidney
Urea
First metabolite to increase in kidney disease
Urea
Good indicator of
1. Nitrogen status
2. State of hydration
Urea
Amount of dietary protein
Kidney’s ability excrete urea
Protein Metabolism
Degree of hydration
Affecting Factors of Blood Urea Level
Condition by which there is an INCREASED IN BLOOD UREA
Uremia
Condition by which ALL NPNS INCREASED
Azoremia
Concentration is expressed only as the ___ content of urea
NITROGEN
BUN (Blood Urea Nitrogen)
____ x BUN = Urea
2.14 x BUN = Urea
____ x 0.467 = BUN
Urea x 0.467 = BUN
Reference Value for Urea
5-38 mg/dL (Serum/plasma)
Laboratory Methods for Urea:
Specimen Requirement
Plasma or Serum (Fasting is preferred; Nonfasting may be used)
Laboratory Methods for Urea:
Tubes to be avoided in BUN (Inactivates Urease)
Citrate
Sodium Fluoride
Laboratory Methods for Urea:
If delay testing, spx must be _____ to avoid bacteria utilization to urea
Refrigeration
Laboratory Methods for Urea:
Chemical Method (Direct) for Urea ; Nonspecific, Simple
Fearson Reaction / Diacetyl Monoximide Method
Laboratory Methods for Urea:
Fearson Reaction / Diacetyl Monoximide Method = Result
YELLOW diazine derivatives
Laboratory Methods for Urea:
Enzymatic Method (Indirect) (2)
- Hydrolysis of Urea by Urease
- Coupled Urease - GLD enzyme Reaction (UV enzymatic)
Laboratory Methods for Urea:
Hydrolysis of Urea by Urease;
Ammonium + Nessler;s Reaction (HgI or KI and gum ghatti) =
Yellow
Hydrolysis of Urea by Urease;
Ammonium + Berthelot’s reaction (Alk. Hypochlorite, Na nitroprusside) =
Blue
Laboratory Methods for Urea:
Specific, more expensive
Uses GLUTAMATE DEHYDROGENASE
Measures disappearance of NADH at 340 nm
Coupled Urease - GLD enzyme
Laboratory Methods for Urea:
Conversion of ammonium to Urea causes increased in conductivity
Conductimetric
Laboratory Methods for Urea:
Reference Method
IDMS
Isotope Dilution Mass Spectrometry
Azotemia:
Reduced Blood Flow
Poor Kidney Perfusion
Pre-renal
Azotemia:
Damage to filtrating structure (tubules, glomerulus)
Renal
Azotemia:
Urinary Tract Obstuction
Post-Renal