TECO DIAGNOSTICS URIC ACID (LIQUID)

1268 N. Lakeview Ave.

Anaheim, CA 92807 REAGENT SET
1-800-222-9880

INTENDED USE STORAGE AND STABILITY

For the quantitative determination of uric acid in serum. The reagent set is stored refrigerated (2 - 8°C). DO NOT FREEZE.
Bring reagent to room temperature before use.
INTRODUCTION
Uric acid is the end product of purine metabolism. Nearly half of REAGENT DETERIORATION
the total uric acid is eliminated and replaced each day by way of The reagent should be discarded if:
urinary excretion and through microbial degradation in the intestinal 1. Turbidity has occurred; turbidity may be a sign of
tract. Increased uric acid levels are commonly associated with both contamination.
nitrogen retention and urea, creatine, and other non-protein 2. There is evidence of discoloration. A slight pink color is
constituents. The quantitation of uric acid is an aid in the diagnosis normal.
of gout, decreased renal function, myeloproliferative disorders, and
other conditions in which the cause for the hyper- uricemia is not SPECIMEN COLLECTION
well known.1 1. Test specimen should be serum and free from hemolysis.
2. Bacterial contamination should be avoided to preserve the loss
Uric acid is most commonly determined by a phosphotungstate of uric acid.
method2 and iron reduction method.3 Due to serum interferences, 3. Uric acid in serum is stable for three (3) days at 2 - 8°C and up
the enzyme uricase has been widely used instead. Uricase is more to six (6) months when frozen.6
specific for uric acid since uricase acts only on uric acid.4,5
INTERFERING SUBSTANCES
PRINCIPLE 1. Bilirubin and ascorbic acid can result in falsely depressed uric
The enzymatic reaction sequence employed in the assay of uric acid levels.
acid is as follows: 2. Lipemic samples may cause falsely elevated uric acid levels.
Uricase 3. Collection tubes containing formaldehyde as a preservative
Uric acid + O2+ 2 H2O ------------ Allantoin + CO2 + H2O2 must be avoided.
4. For a comprehensive review of drug interferences refer to
Peroxidase Young et a1.7
2 H2O2 + 4-Aminoantipyrine + DHBS --------- chromogen + 4 H2O
MATERIALS REQUIRED BUT NOT PROVIDED
Uric Acid is converted by uricase into allantoin and hydrogen 1. Pipette devices
peroxides. The hydrogen peroxide initiates the coupling of 4- 2. Test tubes/rack
aminoantipyrine to 3,5-dichloro-2-hydroxybenzene sulfonic acid 3. Timing device
(DHBS) to form the chromogen which is measured at 520nm and 4. Heating block (37° C)
which is proportional to the amount of hydrogen peroxide generated 5. Spectrophotometer capable of reading at 520 nm
from uric acid.
GENERAL INSTRUCTIONS
REAGENTS
1. Uric acid reagent: 4-Aminoantipyrine 4mM, 3,5 The reagent for uric acid is intended for use either as an automated
Dichloro-2- hydroxybenzenesulfonate 2mM, Stabilizer and procedure on chemistry instruments or as a manual procedure on a
Surfactant, buffer pH 7.5. suitable spectrophotometer.
2. Uric acid standard (5 mg/dl).
AUTOMATED PROCEDURE
WARNINGS AND PRECAUTIONS Refer to appropriate application manual available.
1. For in vitro diagnostic use.
CAUTION: The reagents may be hazardous. Handle in MANUAL PROCEDURE
accordance with good laboratory procedures, which dictate 1. Label test tubes, "reagent blank", "standard", "control",
avoiding ingestion, and eye or skin contact. "unknown", etc.
2. Serum specimens should be considered infectious and handled 2. Pipette 1.0 ml of working reagent into all tubes.
appropriately. 3. Pre-warm all tubes at 37°C for three (3) minutes.
4. Add 0.025 ml (25 µl) of sample to respective tubes and mix.
5. Incubate all tubes at 37°C for ten (10) minutes.
6. After incubation, zero the spectrophotometer with the reagent 3. Comparison: A comparison with another commercial enzymatic
blank at 520 nm and read/record the absorbance of all tubes. uric acid procedure yielded a correlation coefficient of 1.00
(Wavelength range: 500 – 550 nm). with a regression equation of y = 1.02 x - 0.22.
7. Repeat procedure for each sample. 4. Precision studies:
Within Run
* TC MULTI-PURPOSE CALIBRATOR MAY BE USED TO Mean (mg/d]) S.D. C.V.
REPLACE STANDARD 3.9 0.06 2.0%
7.9 0.04 1.0%
ALTERNATE VOLUMES
If the spectrophotometer being used requires a final volume greater Run-to-Run
than 1.0 ml for accurate reading, use 0.05 ml (50 µl) of sample to Mean (mg/d]) S.D. C.V.
3.0 ml of Reagent. Perform the test as described above. 3.9 0.08 2%
8.4 0.50 6%
PROCEDURAL LIMITATIONS
The reagent is linear to 25 mg/dl uric acid. Samples with values
REFERENCES
exceeding 25 mg/dl should be diluted 1:1 with saline, reassayed and
1. Davidsohn, L., and Henry, J.B.: Todd-Sanford Clinical
the results multiplied by two (2). Lipemic samples will give falsely
Diagnosis by Laboratory Method, 15th ed. W.B. Saunders
elevated results and a serum blank must be run.
Company, Philadelphia, PA (1974).
2. Caraway, W.T., Clin. Chem. 4:239 (1963).
Serum blank: Add 0.025 ml (25 µl) of sample to 1.0 ml water. Zero
3. Morin, L.G., Clin. Chem. 20:51 (1974).
the spectrophotometer with water. Read and record absorbance and
4. Fossati, P., Principe L., and Bertia, A., Clin. Chem. 26:227
subtract reading from test absorbance.
(1980).
5. Duncan, P, et al., Clin. Chem. 28:291 (1982).
CALCULATIONS (RATIOMETRIC)
6. Henry, R J. Clinical Chemistry: Principles and Techniques
A = Absorbance
NY, Harper and Row, Second Edition (1974).
A unknown x concentration = value for unknown (mg/dl) 7. Young, D.S, et. al., Clin. Chem. 21:10-4320 (1975).
A standard of standard 8. Tietz, N.W., Fundamentals of Clinical Chemistry,
Philadelphia, W.B. Saunders 729 (1976).
Example: If the unknown A = 0.170, standard A = 0.180,
concentration standard = 5 mg/dl, then:
U582: 01/2018

0.170 x 5 = 4.7 mg/dl Manufactured by:

0.180 TECO DIAGNOSTICS
1268 N. LAKEVIEW AVE.
ANAHEIM, CA 92807
SI UNITS (mmol/L): Multiply the result (mg/dl) by 10 to convert U.S.A.
dl to liter and divide by 168 (the molecular weight of uric acid).

mg/dl x 10 = mmol/L mg/dl x 0.0595 = mmol/L

168

QUALITY CONTROL
It is recommended that controls be included in each set of assays.
Commercially available control material with established uric acid
values may be used for quality control. The assigned value of the
control material must be confirmed by the chosen application.
Failure to obtain the proper range of values in the assay of control
material may indicate either reagent deterioration, instrument
malfunction, or procedural errors.

EXPECTED VALUES
1.5 - 7.0 mg/dl8
It is strongly recommended that each laboratory establish its own
normal range.

PERFORMANCE CHARACTERISTICS
1. Linearity: 25 mg/dl
2. Sensitivity: Based on an instrument resolution of 0.001
absorbance, the present procedure has a sensitivity of 0.03
mg/d1.