Procedure

REDUCING SUGARS IN URINE BY CLINITEST

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Pathology Department	1
Nursing Dept	2

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

I. Method

Clinitest is a reagent tablet based on the Benedict's copper reduction reaction, combining reactive ingredients with an integral heat generating system. The test is used to determine the amount of reducing substances (generally glucose) in urine. Clinitest provides clinically useful information on carbohydrate metabolism. The standard (5-Drop) procedure measures up to 2%sugar; when measurement up to 5% is desired, the 2-Drop method should be used.

II. Principle

Copper sulfate in Clinitest reacts with reducing substances in urine converting cupric sulfate to cuprous oxide. The resultant color, which varies with the amount of reducing substances present, ranges from blue through green to orange. Sodium hydroxide provides the alkaline medium necessary for the reaction. The required heat is provided by the reaction of sodium hydroxide with water and with citric acid.

III. Specimen Collection and Preparation

Prior to collecting the patient’s sample, the patient’s identity must be verified by looking at the arm band. Fresh urine should be used since glucose and other reducing sugars are consumed by bacteria. Refrigerate urine specimens if they cannot be used immediately. Preservatives are not recommended.

IV. Reagents

1 part copper sulfate, 12 parts sodium hydroxide, 4 parts sodium carbonate, 15 parts citric acid, filler and binder.

Stability:

Clinitest tablets are stable for long periods when stored at room temperature in unopened bottle. (Miles Inc. does specify expiration date on each bottle). The tablets are very hygroscopic, and cautions should be taken to avoid exposure to moisture. Label bottles with date opened.

V. Procedure

A. 5-Drop Method

1. Collect urine in clean container. With dropper in upright position, place 5 drops of urine in test tube. Rinse dropper with water and add 10 drops of distilled water to test tube.

2. Drop one Clinitest tablet into test tube. Watch while complete boiling reaction takes place. Do not shake test tube during boiling, or for the following 15 seconds after boiling has stopped.

3. At the end of this 15-second waiting period, shake test tube gently to mix contents. Compare color of liquid to Color Chart. Ignore sediment that may for in the bottom of the test tube. Ignore changes after the 15-second waiting period.

4. Write down the percent (%) result which appears on the color block that most closely matches the color of the liquid.

5. If result is 2% or more, perform the 2-drop method.

B. 2-Drop Method

1. Collect urine in a clean container. With dropper in upright position, place 2 drops of urine in test tube. Rinse dropper with water and add 10 drops of distilled water to test tube.

2. Drop one Clinitest tablet into test tube. Watch while complete boiling reaction takes place. Do not shake test tube during boiling, or for the following 15 seconds after boiling has stopped.

3. At the end of this 15-second waiting period, shake test tube gently to mix contents. Compare color of liquid to Color Chart. Ignore sediment that may form in the bottom of the test tube. Ignore changes after the 15-second waiting period.

4. Write down the percent (%) result which appears on the color block that most closely matches the color of the liquid.

Note: Urine containing more than 2% sugar using the 5-drop method or more than 5% sugar using the 2-drop method may cause a very rapid color change during the boiling and 15-second waiting period. Observe the solution closely during this time to detect "pass-through" color changes. Should these occur, the color will pass rapidly through bright orange to a dark brown or greenish brown. In this case, report the result as over 2% sugar if using the 5-Drop Method or as over 5% sugar if using the 2-Drop Method, and do not compare final color to Color Chart.

VI. Quality Control

A. Reagents

Quantimetrix Normal and Abnormal level. Prepared from normal 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° and 8°C. Controls may be stored at room temperature for up to one month. Label controls with date opened and room temperature expiration date. DO NOT FREEZE.

C. Procedure

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

2. Remove cap and invert bottle, dispense control into a test tube.

3. Wipe off dropper tips and recap controls.

4. Use urine control as you would patient specimen, according to procedure above for the standard 5-Drop Method.

5. Record results on the Quality Control Log Sheet.

D. Frequency

Two levels of quality control (normal and abnormal) should be run every day of patient testing. Controls should also be run whenever a new bottle of Clinitest tablets is opened.

E. Results

Expected values are listed on the Quality Control Log sheet. If controls are not within acceptable limits the following steps should be taken:

1. Check expiration dates of controls and reagent tablets.

2. Repeat procedure with fresh control. If test within range, discard old control.

3. If still out-of-range, open new bottle of Clinitest tablets and repeat test. If test within range, discard bottle of reagent that yielded out-of-control values.

4. If still out of range, contact Point-of-Care Medical Technologist at pager# 4431 or ext. 4431 for further assistance.

5. Do not use Clinitest tablets for patient testing if the Quality Control results are out of range. Send sample down to the Laboratory for analysis.

VII. Results

Clinitest should give negative results with urine specimens from healthy subjects.

Sensitivity: this test will be positive when glucose or other reducing substances are in concentrations as low as 1/4 % (.25 g/dL)

Positive results should be confirmed by the laboratory and reported to the physician immediately.

Critical Values are up to the assessment of the physician.

VIII. Limitations

§ Clinitest is not specific for glucose; will react with sufficient quantities of any reducing substance.

§ Low specific gravity urines containing glucose may give slightly elevated results.

§ The metabolites of some sulfa drugs and methapyriline compounds may interfere with the sensitivity of Clinitest 2-Drop Method. These substances are not known to interfere at glucose levels of 1/2% or higher.

§ High protein concentrations extend boiling time, increase foaming and may make visual comparison difficult.

§ The presence of X-Ray contrast media in urine may produce reduced glucose results and false-negative results.

IX. Competency Checks

Competency checks are performed during MYR yearly by the POC Medical Technologist or a validated nurse.

X. References:

Davidson I, Henry JB (eds): Clinical Diagnosis by Laboratory Methods, 15th Edition. WB Saunders, Philadelphia, 1974. 54-59.

Clinitest Reagent Tablets, Package Insert, Miles Inc., Elkhart, IN, September, 1987.

The dropper Plus, Package Insert, Quantimetrix Corporation, Hawthorne, CA. October, 1993.