Procedure

GLUCOSE AND KETONES IN URINE WITH CHEMSTRIP UGK URINE TEST STRIPS

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Nursing Department	1
Pathology Department	1

PRECAUTION: WHILE PERFORMING THIS PROCEDURE, THE FOLLOWING

SAFETY MEASURES MUST BE TAKEN: GLOVES MUST BE WORN; SMOKING, EATING, DRINKING, APPLICATION OF COSMETICS, AND MANIPULATION OF CONTACT LENSES ARE PROHIBITED IN ALL TECHNICAL WORK AREAS. REFER TO THE UNIVERSAL PRECAUTIONS POLICIES.

CLIA Complexity: Waived-Definitive

I. Principle

Chemstrip uGK test strips are for the semiquantitative visual estimation of glucose and ketones in urine.

Glucose:

The glucose reagent area has two distinct zones of different reagent concentrations specifically designed to provide optimal sensitivity to urine glucose levels ranging from 100 to 5,000 mg/dL. Both zones of the reagent area contain the enzymes glucose oxidase and peroxidase, and the color indicator tetramethylbenzidine. D-glucose is oxidized to gamma-D-gluconolactone with glucose oxidase acting as a catalyst. The hydrogen peroxide that results from the reaction oxidizes the indicators in the presence of peroxidase. The intensities of the colors formed are proportional to the glucose concentration of the specimen.

Ketones:

The detection of ketone bodies in urine is based on the method attributed to Legal.

II. Specimen

Prior to collecting the patient’s sample, the patient’s identity must be verified by looking at the arm band. If it is an outpatient, verbally verify patient’s name and date of birth with patient or parent/guardian. Collect urine in a clean container that will allow complete immersion of test strip area. Test as soon as possible after collection. Do not centrifuge specimen. If testing cannot be performed within one hour after collection, the specimen should be refrigerated immediately at 2-8⁰C and returned to room temperature prior to testing. Mix thoroughly before testing.

III. Reagents

Chemstrip uGK Urine Test Strips (Cat. No. 00513).

Store at room temperature below 30°C; do not freeze.

Label vial with date opened; do not use after expiration date.

Caution: Test strips contain nitroferricyanide. Do not touch the reagent pads with skin or mucous membranes; if contact occurs flush with large amounts of water.

Timer or watch with a second hand

IV. Procedure

1. Collect fresh urine specimen in clean, dry container. Mix well before testing.

2. Remove one test strip from bottle and replace cap immediately. Completely immerse reagent area in urine and remove immediately to avoid dissolving out reagents.

3. While removing, run the edge of the strip against the rim of the urine container to remove excess urine.

4. Start timing for two minutes. After two minutes, match the colors on the test strip with the color blocks printed on the vial label. Any color changes after three minutes are not important.

5. DO NOT COMPARE TEST STRIP FROM ONE VIAL WITH THE COLOR CHART ON ANOTHER VIAL (DIFFERENT LOT NUMBER). THIS COULD CAUSE MISINTERPRETATION. EACH COLOR CHART IS MADE TO MATCH THE TEST STRIPS FOR THAT LOT NUMBER.

6. When the colors of the glucose test patch are between the color blocks on the vial, then glucose test result is between those color blocks. Compare both glucose color blocks at the same time.

7. If the ketone turns from beige to violet, the test is positive.

V. Quality Control

A. Reagents

Quantimetrix urine dipstick controls, normal and abnormal level; prepared from human urine to which is added predetermined amounts of chemicals. Liquid, ready-to-use.

B. Storage and Stability

Stable until expiration date stated on label, when stored between 2° to 8°C. Controls can be stored up to one month at room temperature. Label control vials with open date and room temperature expiration date. DO NOT FREEZE.

C. Procedure

1. On initial use, remove the control tube from the refrigerator and allow to reach room temperature prior to testing.

2. Remove cap and invert bottle. While holding reagent strip, gently squeeze the sides of the dropper bottle and touch the tip of the bottle to the test pad. Thoroughly saturate the reagent pads. Turn the dipstick on its side and drain excess control onto absorbent material.

3. Read the dipstick according to the procedure above.

4. Wipe off dropper tips and recap controls. The controls can be stored at room temperature for up to one month when not in use.

5. Record results on the Quality Control Log Sheet.

D. Frequency

Two levels of quality control (normal and abnormal) should be run once a week. Controls should also be run whenever a new vial of uGK Reagent Strips is opened.

E. Troubleshooting

If quality control results are not within the acceptable limits the following steps should be taken:

1. Confirm that the strips and controls are within the opened expiration dates shown on the label.

2. Repeat test with fresh control material. If still out of range, go to step 3.

3. Repeat test with new vial of test strips.

4. Discard any controls or reagent strips which gave invalid test results.

5. Do not use strips for patient testing if quality control results are out of range.

VI. Expected Results

Glucose or ketones should not be detected in normal urine. A positive reaction indicates a need for further diagnostic evaluation of the patient. Critical Values are up to the assessment of the physician.

VII. Limitations

Glucose:

False negative or falsely lowered glucose readings may occur rarely at high concentrations of ascorbic acid. Highly colored urine (i.e. due to certain medications or bilirubin) may the color reaction and prevent accurate readings. Glucose values must be determined within three minutes of starting the test.

Ketones:

2-Mercaptoethane sulphonate sodium and other sulfhydryl-containing compounds may cause false positive results. Ketone values must be determined within the specified three minute time limits.

VIII. Competency Checks

Competency checks are performed during at initial orientation, after 6 months of employment, and yearly thereafter by the POC Medical Technologist or a validated nurse.

IX. References

1. Legal E. Chem Centr. 14:652 (1883)

2. Zweig M. Clin. Chem. 32/4, 674-677 (1986)

3. Chemstrip uGK Urine Test Strips, package insert. Boehringer Mannheim Diagnostics. Indianapolis, IN. 1988.

4. The dropper Plus Urine Dipstick Control Kit, package insert. Quantimetrix Corporation, Hawthorne, CA. September, 1993.