Uric acid is the end product of purine metabolism. Uric acid is excreted to a large degree by the kidneys and to a smaller degree in the intestinal tract by microbial degradation. Increased levels are found in Gout, arthritis, impaired renal functions.and starvation. Decreased levels are found in Wilson’s disease, Fanconis syndrome and yellow atrophy of the liver.
Uricase converts uric acid to allantoin and hydrogen peroxide. The hydrogen peroxide formed further reacts with a phenolic compound and 4 aminoantipyrine by the catalytic action of peroxidase to form a red coloured quinoneimine dye complex. Intensity of the colour formed is directly proportional to the amount of uric acid present in the sample.
Normal reference values
|Male||3.4 – 7.0 mg/dl|
|Female||2.5 – 6.0 mg/dl|
|Pack Sizes||25 ml, 75 ml, 2 x 75 ml, 2 x 150 ml|
|L1 : Buffer Reagent||20 ml, 60 ml, 2 x 60 ml, 2 x 120 ml|
|L2 : Enzyme Reagent||5 ml, 15 ml, 2 x 15 ml, 2 x 30 ml|
|S : Uric Acid Standard (8 mg/di)||5 ml, 5 ml, 5 ml, 5 ml|
All Reagents are ready to use.
Reagents Storage/ stability:
Contents are stable at 2-8°C till the expiry mentioned on the labels.
Serum, plasma. Uric Acid is reported to be stable in the sample for 3 -5 days when stored at 2-8°C.
|Wavelength||520 nm (Hg 546 nm)|
|Zero Setting||Reagent Blank|
|lncub. Temp.||37°C I R.T|
|lncub. Time||5 min./ 15 min.|
|No. of read.||—-|
|Sample Vol.||0.02 ml|
|Reagent Vol.||1.00 ml|
Pipette into clean dry test tubes labelled as Blank (B), Standard (S), and Test (T):
|Addition Sequence||Blank (B)||Standard (S)||Test (T)|
|L1 : Buffer Reagent||800 μl||800 μl||800 μl|
|L2 : Enzyme Reagent||200 μl||200 μl||200 μl|
|Distelled Water||20 μl||–||–|
Mix well and incubate at 37°C for 5 min. or at R.T. (25°C) for 15 min. Measure the absorbance of the Standard (Abs.S), and Test Sample (Abs.T) against the Blank, within 30 Min.
This procedure is linear upto 20 mg/di. If values exceed this limit, dilute the serum with normal saline (NaCl 0.9%) and repeat the assay. Calculate the value using the proper dilution factor.
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