NPNs Flashcards
The concentration of nitrogen-containing compounds
in this protein-free filtrate was quantified spectrophotometrically by converting
nitrogen to ammonia and subsequent reaction with ________ reagent to produce a yellow color
Nessler’s reagent (K2[HgI4)
Most abundant NPN to least
Urea Amino acids Creatinine Creatine Ammonia
the major excretory product of protein metabolism.
Urea
Small quantities of urea
(<10% of the total) are excreted through the:
GI tract & skin
Reference method for Urea
isotope dilution mass spectrometry (IDMS)
Analytic methods (Urea): Conversion of unionized urea to NH4 & CO2-3 results in increased conductivity
Conductometric
Analytic methods (Urea): Enzymatic reaction of NH4 2-oxoglutarate & NADH to form glutamate & NAD+
GLDH-couple enzymatic
Normal value of Urea Nitrogen (plasma/serum)
6-20mg/dl
Normal value of Urea Nitrogen (urine)
12-20g/d
An elevated concentration of urea in the blood is called
azotemia.
Very high
plasma urea concentration accompanied by renal failure is called
uremia or the
uremic syndrome.
is a result of reduced renal blood flow. Less blood is
delivered to the kidney; consequently, less urea is filtered.
Prerenal azotemia
Decreased renal function causes an increase in plasma urea concentration as
a result of compromised urea excretion.
renal azotemia
can be due to
obstruction of urine flow anywhere in the urinary tract by renal calculi, tumors
of the bladder or prostate, or severe infection.
Postrenal azotemia
The major causes of decreased plasma urea concentration include
low
protein intake and severe liver disease. Pregnancy
Urea: Increased
Urea N/C ratio: High
Crea: Normal
Prerenal
Urea: Increased
Urea N/C ratio: High
Crea: Increased
Postrenal
product of catabolism of the purine nucleic acids.
Uric acid
Renal excretion
accounts for about __% of uric acid elimination;
70
Nearly all of the uric acid in plasma is present as
monosodium urate.