Determination of Uric Acid

Principle:

   Uric acid  in alkaline solution reduces phosphotungestate  to tungesten blue. phosphotungestic acid is used as a deproteinizing and color reagent.

Normal value: Males: 2-7 mg/dl

                         Females: 2-6 mg/dl

Reagents:

Reagent I: deproteinizing and color reagent

Reagent II: uric acid standard

Additional reagent: sodium carbonate.

Sample preparation:

Serum or Plasma.

Deproteinization of the sample:

1- Pipette into centrifuge tubes 3 ml of reagent 1 + 0.3 ml serum or heparinized plasma.

2-Mix well, let stand for 10 minutes at room temperature and centrifuge.

Colour Reaction:

Carefully pour into dry test tubes.

Wave length: 680-710 nm.

Incubation temperature: 25°c.

Measurement: against blank.

Pipette into test tubes:

Mix vigorously, let to stand for 20 min. at 25 °C. Measure the absorbance of Sample and Standard against Blank.

Calculation:

Uric Acid concentration in mg% =   A sample / A standard   x 10

Interpretation:

Increased excretion of uric acid occurs in gout.