NPNs Flashcards
Major NPN found in the blood (45-50% of total NPN)
UREA
Major excretory product from protein metabolism
UREA
Synthesized in the liver from CO2 + Ammonia
generated during protein catabolism
UREA
Urea is synthesized in the liver from CO2 + Ammonia generated during ___
protein catabolism
Urea cycle process in mitochondria will produce ?
Carbamoyl Phosphate and Citrulline
The enzyme ___ is important to the release of urea
arginase
How many percent of urea is reabsorbed?
40%
How many percent of urea is excreted in the urine?
50%
How many percent of urea is excreted through GI and skin?
<10%
very high levels of plasma urea accompanied by renal failure
Uremia/uremic syndrome
an elevated concentration of urea in the
blood
Azotemia
Decreased blood flow to kidneys
PRERENAL AZOTEMIA
Possible causes (which affect urea transport)
○ Congestive heart failure
○ Shock, hemorrhage
○ Dehydration
○ Other factors resulting in significant marked
decreased volume
PRERENAL AZOTEMIA
● Acute/chronic renal failure
● Glomerulonephritis
● Tubular necrosis
● Other intrinsic renal disease
RENAL AZOTEMIA
Urinary tract obstruction caused by:
○ Renal calculi
○ Tumors of the bladder/prostate
○ Severe infection
POSTRENAL AZOTEMIA
High urea : Normal creatinine
PRERENAL AZOTEMIA
High urea : High creatinine
RENAL AZOTEMIA
Normal urea : High creatinine
POSTRENAL AZOTEMIA
Normal Urea Nitrogen : Creatinine ratio
10:1 - 20:1
Decreased urea nitrogen: creatinine ratio
PRERENAL AZOTEMIA
Product of Fearon’s reaction
yellow diazine derivative
Also known as Friedmans Method or Xanthydrol
Method
Fearon’s reaction
CONDENSATION WITH DIACETYL MONOXIME METHOD
Fearon’s reaction
Product in REACTION WITH 0PHTHALALDEHYDE AND NAPHTHYLETHYLENEDIAMINE
chromogen or colored product
Product in MICROKJELDAHL NESSLER METHOD
yellow compound
All enzymatic methods use what enzyme?
Urease
Product in UREASEBERTHELOTS METHOD
indophenol blue
Coupled Enzymatic in Urea Determination
UREASE-L-GLUTAMATE DEHYDROGENASE METHOD (GLDH METHOD)
reference method for measuring urea
ISOTOPE DILUTION MASS SPECTROMETRY IDMS
If plasma will be used for urea determination, any additive maybe used except ___/____ which
interferes with urease and ammonium ions
sodium fluoride / sodium citrate
Reference Ranges for Urea Nitrogen
Plasma or Serum: ____ mg/dL
Urine, 24hr: ____ g/d
Plasma or Serum: 6-20 mg/dL
Urine, 24hr: 12-20 g/d
product of catabolism of purines bases Adenine and
Guanine)
URIC ACID
How many percent of uric acid is reabsorbed in the proximal tubules
98-100%:
How many percent of uric acid is excreted in the distal tubules
<1%
Uric acid excretion
Renal excretion: ___ %
GI excretion: ___%
Renal excretion: 70%
GI excretion: 30%
Uric acid is Relatively insoluble in plasma as monosodium urate at pH ___
pH 7
At concentrations ____ mg/dL, plasma is saturated,
urates crystals may form in the tissues
6.8 mg/dl
At pH ___ , uric acid crystals may form
pH 5.75
High concentrations accumulate in the joints and
tissue resulting in inflammation
Gouty Arthritis
Increased: hyperuricemia ____ mg/dL
6.0 mg/dL
Patients have pain and inflammation of the joints
caused by precipitation of sodium urates
GOUT
Deposition of Uric Acids in tissues and joints
TOPHI
Seen in patients undergoing chemotherapy for
leukemia, lymphoma, multiple myeloma, polycythemia
INCREASED NUCLEAR BREAKDOWN
inhibit xanthine oxidase
allopurinol
Enzyme that is targeted by Allopurinol to
lower your Uric Acid
Xanthine Oxidase
X-linked genetic disorder (seen only in males)
LESCH NYHAN SYNDROME
caused by the complete deficiency of
hypoxanthine–guanine phosphoribosyltransferase
(HGPRT)
LESCH NYHAN SYNDROME
Lack of this enzyme prevents the reutilization of
purine bases in the nucleotide salvage pathway
hypoxanthine–guanine phosphoribosyltransferase
Defective tubular reabsorption (Fanconi’s
Syndrome)
HYPOURICEMIA
Overtreatment with allopurinol
HYPOURICEMIA
Chemotherapy with 6-mercaptopurine or
azathiopurine (inhibits de novo purine
synthesis)
HYPOURICEMIA
Caraway Method/ Henrys Method
DIRECT REDOX METHOD
Uses phosphotungstic acid and produces tungsten blue
Caraway Method/ Henrys Method
Based on the oxidation of UA in PFF (Protein-Free
Filtrate) and reduction of PTA (Phosphotungstic Acid)
Caraway Method/ Henrys Method
Reagent is uricase or urate oxidase
URICASE METHOD (BLAUCH AND KOCH)
2 enzymes:
○ First reaction: uricase
○ Second reaction: peroxidase
COUPLED ENZYMATIC METHOD
proposed reference method for uric acid determination
ISOTOPE DILUTION MASS SPECTROMETRY IDMS**
____ or ____ should not be used in uric acid specimen
EDTA or fluoride
Uric Acid Plasma or Serum Specimen
Male (Adult): ___ mg/dL
Female (Adult): ___ mg/dL
Male (Adult): 3.5-7.2 mg/dL
Female (Adult): 2.6-6.0 mg/dL
Waste product of creatine formed during normal
muscle metabolism
CREATININE
Is formed from creatine and creatine phosphate in
muscle and is excreted into the plasma at a constant
rate related to muscle mass
CREATININE
Plasma creatinine is ____ related to glomerular
filtration rate
inversely
Produced by the liver and pancreas from arginine,
glycine, methionine
CREATINE
CREATINE is produced by the liver and pancreas from ____?
arginine, glycine, methionine
creatine enters the bloodstream and is distributed in cell especially in the muscle where it is converted to
phosphocreatine
measure of the amount of creatinine eliminated
from the blood by the kidneys
Creatinine clearance
Creatinine + NaOH & picric acid alkaline picrate
complex
JAFFE REACTION
Reagents in Jaffe with Adsorbent
○ Fullers Earth – ____
○ Lloyds reagent – ____
○ Fullers Earth – aluminium magnesium silicate
○ Lloyds reagent – sodium aluminum silicate
CREATININE DETERMINATION CHEMICAL produced what colored compound
purple-colored compound
Accepted Reference Method for creatinine
IDMS (Isotope Dilution Mass Spectrophotometry)
____ causes a negative bias in both Jaffe and
enzymatic methods.
Bilirubin
___causes a positive bias in some enzymatic
methods.
Lidocaine
____ will interfere in enzymatic methods that use peroxidase as a reagent.
Ascorbate
Produced from the deamination of amino acids
AMMONIA
Consumed by the parenchymal cells of the liver in the production of Urea
AMMONIA
Most ammonia in the blood exists as
Ammonium Ion
(Blood sugar drops and blood ammonia and
acidity increases) post viral with aspirin
resulting in hepatic dysfunction due to fatty
infiltration of the liver.
Reyes syndrome
Exploited the volatility of ammonia to separate the
compound in microdiffusion chamber
CONWAY METHOD
Most common on automated instruments in Ammonia determination
ENZYMATIC METHOD - CATALYZED BY GLDH
Venous blood for Ammonia specimen should be obtained without trauma and placed on ___ immediately
ice
Ammonium salts, asparaginase, barbiturates,
diuretics, ethanol, hyperalimentation, narcotic
analgesics, and some other drugs may ____
ammonia in plasma
increase
Diphenhydramine, Lactobacillus acidophilus, lactulose, levodopa, and several antibiotics ____ ammonia concentrations.
decrease