AUBF Chemical Analysis P1

State the 10 parameters in chemical examination of urine.

pH, protein, glucose, ketones, blood, bilirubin, urobilinogen, nitrite, leukocytes and specific gravity

True or False: The chemical examination of urine only tests for glucose and protein.

False.

Identify the term: A firm plastic strip with pads impregnated with chemicals that react with urine.

Reagent strip.

What is the purpose of reagent strips in urinalysis?

To detect specific chemical analytes in urine.

Fill in the blank: Reagent strips must be stored in a ________, dry container.

cool.

True or False: Reagent strips should be exposed to moisture and volatile fumes.

False.

What is the recommended storage temperature for reagent strips?

Room temperature below 30°C.

Fill in the blank: Do not use reagent strips past their ________ date.

expiration.

True or False: Each test area on the reagent strip is specific to a particular analyte.

True.

Identify the type of strip that uses ethylene glycol-bis-tetraacetic acid for specific gravity measurement.

Chemstrip.

What reagent is used in Multistix for specific gravity?

Poly (methyl vinyl ether/maleic anhydride).

True or False: Specific gravity pad turns from yellow to blue as SG increases.

False.

What is the sensitivity range of the SG reagent pad?

1.000 to 1.030.

True or False: Protein concentration above 100 mg/dL may give a false positive SG.

True.

Identify one condition that may cause a false positive specific gravity.

Ketoacidosis.

Fill in the blank: Highly alkaline urine with pH >________ can cause false negative SG results.

6.5.

True or False: For Multistix, if pH ≥ 6.5, 0.005 must be added to SG reading.

True.

What is the clinical significance of SG in monitoring hydration?

It helps assess hydration and renal concentration ability.

Identify the condition characterized by a low SG due to inability to concentrate urine.

Diabetes insipidus.

True or False: SG helps determine if a urine specimen is too dilute.

True.

What is the reaction principle of the pH reagent pad?

Double indicator system.

Identify the two indicators used in the pH pad of reagent strips.

Methyl red and bromthymol blue.

True or False: The pH pad changes from red-orange to deep blue.

True.

Fill in the blank: pH values range from ________ to ________ on the multistix reagent strip.

5.0 to 8.5.

What is the main clinical significance of pH in urine analysis?

Assessing acid-base regulation.

Identify one clinical application of urine pH testing.

Evaluation of renal tubular acidosis.

True or False: A urine pH of 4.0 or 9.0 is normal and doesn't need verification.

False. pH <4.5 is physiologically impossible.

What confirms an abnormal pH outside of reagent strip range?

pH meter.

Identify the test principle for protein detection in urine.

Protein (Sorensen’s) error of indicators.

True or False: Protein pad detects both albumin and globulins equally.

False. Only albumin.

Fill in the blank: The protein reagent pad is most sensitive to ________.

Albumin.

What is the color change on the protein pad from negative to positive?

Yellow to blue-green.

What are the reagents used in Multistix for protein?

Tetrabromophenol blue and citrate buffer.

True or False: For chemstrip, the protein reagent pad has a sensitivity of 15-30 mg/dL albumin.

False. Multistix.

The analyte most indicative of renal diseases (early detection).

Protein.

True or False: Blood contamination will not interfere with protein pad reading.

False.

It is caused by conditions affecting the plasma prior to it reaching the kidney and not indicative of actual renal disease.

PRE-RENAL PROTEINURIA

Also known as TRUE RENAL DISEASE.

Renal Proteinuria.

What condition is described?

Protein can be added to a urine specimen as it passes through the structures of the lower urinary tract (after the kidney).

Postrenal Proteinuria.

What interferences cause false negative results in protein pad?

✓ Proteins other than albumin

✓ Microalbuminuria

Fill in the blank: The most common sugar detected in urine is ________.

Glucose.

True or False: The glucose pad is based on a double sequential enzyme reaction.

True.

Identify the enzymes used in the glucose reagent pad.

Glucose oxidase and peroxidase.

What are the reagents used in the glucose test pad? (multistix)

Glucose Oxidase, Peroxidase, Potassium Iodide

Fill in the blank: Multistix glucose reagent pad sensitivity is ________ mg/dL.

75-125.

True or False: Reducing substances can cause false positive glucose pad results.

False. False negative.

What is the color range of chemstrip glucose test pad?

Yellow to green.

Identify one cause of false negative glucose result.

✓ High levels of Ascorbic Acid (Reducing Agent)

✓ High S.G, High levels of Ketones

✓ Low Temperatures (reduce enzyme activity)

✓ Improperly preserved urine

True or False: High ketone levels interfere with the glucose pad.

True.

Glucose: Clinical Significance:

Shows INCREASED Blood Glucose; and INCREASED Urine Glucose

Hyperglycemia-Associated Disorders

Glucose: Clinical Significance:

Shows NORMAL Blood Glucose; and INCREASED Urine Glucose

Renal-Associated Disorders (Defective Tubular Reabsorption)

What is the renal threshold of glucose?

160-180mg/dL

What are the renal-associated disorders?

✓ Fanconi’s Syndrome

✓ End-stage Renal Disease (ESRD)

✓ Cystinosis, Heavy Metal Poisoning, Genetic Disorders

✓ Pregnancy

✓ Osteomalacia (bone softening, due to Vitamin D Deficiency)

What is the sensitivity value of a chemstrip glucose pad?

40 mg/dL

What is an interference that causes a false positive result in a glucose pad?

✓ Contamination by Oxidizing Agents (ex. Detergents (Bleach), Peroxides)

What is the semi-quantitative result of a glucose value of 0.25% (250mg/dL)?

1+

What is the semi-quantitative result of a glucose value of 2.0% (≥2000 mg/dL)?

4+

What is the semi-quantitative result of a glucose value of 1.0% (1000 mg/dL)?

3+

Fill in the blank: Ketones are intermediate products of ________ metabolism.

Fat.

Identify the three ketones found in urine.

Acetone, acetoacetic acid, beta-hydroxybutyric acid.

True or False: The reagent strip only detects beta-hydroxybutyric acid.

False. Not detected in reagent strip.

What ketone is primarily detected by the reagent strip?

Acetoacetic acid.

Identify the reagent used in the ketone pad.

Sodium nitroprusside/Nitroferricyanide (both multistix & chemstrip)

Fill in the blank: A purple color on the ketone pad indicates a ________ result.

Positive.

True or False: Ketones in urine can suggest diabetic ketoacidosis.

True.

Identify one non-diabetic condition that causes ketonuria.

Starvation.

What can cause false positives in the ketone test pad?

✓ Highly Pigmented Urine

✓ Compounds containing free sulfhydryl groups (MESNA)

✓ High quantities of Levodopa (Parkinson’s Disease)

✓ Phthalein Dyes

True or False: Manual reading of reagent strips is more accurate than automated.

False. Automated standardized results and minimizes human error caused by different color perception.

What interferes with accurate visual reading of reagent strips?

Color blindness, lighting, and timing.

Fill in the blank: Quality control of reagent strips should be done using ________ controls.

Positive and negative.

Identify one storage requirement for reagent strips.

Protect from moisture and light.

True or False: Reagent strips should be tested with distilled water for QC.

False.

What is the ideal sample for reagent strip testing?

Freshly voided urine.

Fill in the blank: Reagent strips should be read at the specified ________ for each analyte.

time.

Identify one way to avoid runover between reagent pads.

Horizontally blot edge on absorbent paper.

True or False: Excess urine left on the strip may cause color mixing.

True.

Fill in the blank: The ________ pad detects acid-base status.

pH.

True or False: Multistix and Chemstrip have different ranges for SG and pH.

True.

What is the expected negative result color for protein on reagent strip?

Yellow.

Fill in the blank: Ketone strips detect primarily ________.

Acetoacetic acid.

Identify one metabolic disorder associated with ketonuria.

Diabetic ketoacidosis.

True or False: Ketones appear in urine during starvation or fasting.

True.

True or False: All abnormal reagent strip results must be confirmed.

True.

Fill in the blank: A fresh urine sample should be tested within ________ of collection.

2 hours.

True or False: Refrigeration can alter reagent strip results.

True.

What should be done before testing refrigerated urine?

Bring to room temperature.

True or False: Presence of bacteria may alter pH and glucose readings.

True.

What is a major limitation of reagent strips?

Only semi-quantitative results.

Identify the advantage of automated reagent strip readers.

Increased accuracy and standardization.

True or False: Automated strip readers eliminate human reading errors.

True.

What is the common source of error in protein testing?

Highly alkaline urine.

Fill in the blank: The color intensity on the pad is directly proportional to the ________ of the analyte.

concentration.

True or False: Proper timing is critical in interpreting strip reactions.

True.

What is the result of reading the glucose pad too late?

False positive.

Fill in the blank: All reagent strips must be ________ before use.

inspected.

Identify the term: A quality measure ensuring reagent strips are functioning properly.

Quality control.

True or False: Daily QC is required for reagent strip use in the laboratory.

True.

True or False: Specific gravity on the strip correlates well with refractometry.

False.

Identify a condition that causes low specific gravity.

Diabetes insipidus.

Fill in the blank: A pH above 8.5 on strip suggests ________ contamination or improper storage.

bacterial.