Podcast
Questions and Answers
What is the principle behind the Multistix test method?
What is the principle behind the Multistix test method?
- Oxidation-reduction reaction
- Enzymatic reaction
- Ehrlich aldehyde reaction (correct)
- Lipid precipitation method
Which substance is NOT reliably detected by the Ehrlich reagent-based method in Multistix?
Which substance is NOT reliably detected by the Ehrlich reagent-based method in Multistix?
- Urobilinogen
- Procaine
- Porphobilinogen (correct)
- Indole
How does the Chemstrip method differ from the Multistix method?
How does the Chemstrip method differ from the Multistix method?
- Chemstrip is less sensitive
- Chemstrip detects only indole
- Chemstrip does not require an acid medium
- Chemstrip uses a different reagent system (correct)
What color indicates the presence of urobilinogen in the Multistix method?
What color indicates the presence of urobilinogen in the Multistix method?
What is the normal range of urobilinogen levels detected by Multistix?
What is the normal range of urobilinogen levels detected by Multistix?
Which condition can lead to false results in both Multistix and Chemstrip tests?
Which condition can lead to false results in both Multistix and Chemstrip tests?
Why is a freshly voided sample preferred for urobilinogen testing?
Why is a freshly voided sample preferred for urobilinogen testing?
What is the detection capability of the Chemstrip urobilinogen test?
What is the detection capability of the Chemstrip urobilinogen test?
What will the Chemstrip method produce in the presence of urobilinogen?
What will the Chemstrip method produce in the presence of urobilinogen?
What condition might lead to an unreliable detection of urobilinogen?
What condition might lead to an unreliable detection of urobilinogen?
Flashcards
Ehrlich reagent method
Ehrlich reagent method
A test for urobilinogen in urine that uses a reagent strip impregnated with p-dimethylaminobenzaldehyde, which reacts with urobilinogen to produce a reddish-brown color.
Ehrlich-reacting substance
Ehrlich-reacting substance
A substance that reacts with the Ehrlich reagent, producing a false positive result for urobilinogen.
Chemstrip urobilinogen test
Chemstrip urobilinogen test
A test for urobilinogen in urine that uses a reagent strip impregnated with 4-methoxybenzene-diazonium-tetrafluoroborate, which couples with urobilinogen to form a red azo dye.
4-methoxybenzene-diazonium-tetrafluoroborate
4-methoxybenzene-diazonium-tetrafluoroborate
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Urobilinogen
Urobilinogen
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Urobilinogenuria
Urobilinogenuria
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Phenazopyridine
Phenazopyridine
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Orange-red urine
Orange-red urine
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Diazonium compound
Diazonium compound
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Specific
Specific
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Study Notes
Reagent Strip Methods for Urobilinogen Testing
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Multistix Method: Employs the Ehrlich aldehyde reaction. The test area contains an acid buffer and p-dimethylaminobenzaldehyde. Urobilinogen reacts to form reddish brown color. Normal range is 0.2-1 mg/dL.
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Color Range: Light yellow to red-brown.
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Limitations: Not specific for urobilinogen. Detects other substances reacting with Ehrlich reagent: porphobilinogen, p-aminosalicylic acid metabolites, sulfonamides, procaine, 5-hydroxyindoleacetic acid, indole, methyldopa. Not reliable for porphobilinogen.
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Chemstrip Method: Uses 4-methoxybenzene-diazonium-tetrafluoroborate, which forms a red azo dye with urobilinogen in an acidic environment.
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Detection Limit: Approximately 0.4 mg/dL.
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Reading Time: Results are read within 10-30 seconds.
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Specificity: Unlike Multistix, Chemstrip is more specific for urobilinogen.
Factors Affecting Reagent Strip Tests
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Sample Stability: Freshly voided urine is preferred as urobilinogen is unstable and can form non-reactive urobilin in acidic urine.
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Drug Interference: Metabolites of drugs like phenazopyridine (Pyridium) and Azo-Gantrisin can affect the tests by causing false positives or masking the reaction with urobilinogen (changing the urine color, for example).
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Other Interferences: Bilirubin and blood usually do not interfere but bilirubin can sometimes cause a green color.
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