Uric Acid Flashcards
• Metabolic waste product of purine metabolism
– from the breakdown of ingested nucleic acids
– from tissue destruction
Uric Acid
Uric Acid
• Metabolic waste product of____
– from the breakdown of ingested___
– from___ destruction
purine metabolism
nucleic acids
tissue
Uric acid
• Filtered by the glomerulus
•_____ reabsorbed by PCT
• Small amount are secreted by DCT
98-100%
• Uric acid is formed from the breakdown of _____and is an end product of purine metabolism.
• Uric acid is transported by the plasma from the____ to the _____, where it is filtered and where about 70% is excreted.
• The remainder of uric acid is excreted into the___ tract.
nucleic acids
liver to the kidney
Gl
Gmp
Amp
guanosine monophosphate
adenosine monophosphate
GMP > nucleotidase > Guanosine > nucleosidase > Guanine > guanine deaminase > _____
Xanthine
AMP nucleotidase > Adenosine > adenosine deaminase > Inosine > nucleosidase > Hypoxanthine > xanthine oxidase > ____
Xanthine
Xanthine > ____ > Uric Acid
xanthine oxidase
Uric Acid
• Present as_____ in the plasma
monosodium urate
Relatively____ (blood pH)
– At concentrations greater than_____/dL, the plasma is saturated
• Resulting to urate crystals formations
• Precipitation in the tissues and joints
insoluble
6.8 mg/ dL
Uric Acid analytical method
- Caraway Method
- Uricase Method
- Couple Enzymatic Methods
– Based on the oxidation of UA in PFF, with subsequent reduction of phosphotungstic acid to tungsten blue
Caraway Method
Sodium carbonate
– Provides alkaline pH for color development
– Lacks specificity
Caraway method
– Uricase catalyzes the oxidation of UA to allantoin
– Measures the differential absorption of uric acid and allantoin at____
Uricase Method
293 nm
– More specific
– hemoglobin and xanthine can cause negative interference
Uricase method
Uricacid + H,0+02»_space;> allantoin + CO, + H,02
Uricase
– Measures the hydrogen peroxide produced as UA is converted to allantoin
• Peroxidase or catalase
– Catalyze a chemical indicator reaction
Couple Enzymatic Methods
Couple Enzymatic Methods
Interference:
• Bilirubin and ascorbic acid (destroy peroxide)
• Uric acid is oxidized to allantoin by____.
•The generated _____reacts with 4-aminophenazone/ESPT to quinoneimine.
uricase
hydrogen peroxide
specimen requirement
Heparinized Plasma, serum, or urine
specimen requirement
• Should be removed from cells ASAP to prevent dilution by intracellular contents
• Fasting is not required
• Avoid lipemic and hemolyzed specimens
• May be refrigerated for 3-5 days
Serum
interfering substances
• High bilirubin Concentration
• Ascorbic acid
• Drugs
- Salicylates
- Thiazides
- Falsely decrease results to Peroxidase methods
- Addition of Potassium ferricvanide and ascorbate oxidase
• High bilirubin Concentration
• Ascorbic acid
• Falsely increase results
Drugs
- Salicylates
- Thiazides
