Biochemistry Tests: Xanthoproteic and Fouchet's Tests

Questions and Answers

What indicates the presence of bilirubin in urine during Fouchet's test?

Elimination of trichloroacetic acid

Formation of white precipitate

Presence of barium sulphate

Development of a green color (correct)

What role does trichloroacetic acid play in Fouchet's test?

It releases adsorbed bilirubin from precipitate. (correct)

It forms barium chloride complex.

It acts as a precipitating agent.

It oxidizes yellow bilirubin to green biliverdin.

Which component is responsible for oxidizing bilirubin in Fouchet's test?

Trichloroacetic acid

Sodium chloride

Ferric chloride (correct)

Barium chloride

What does the presence of yellow bilirubin indicate in a patient's urine?

Potential liver dysfunction Signup and view all the answers

What is formed when barium chloride is added to urine in the context of Fouchet's test?

Barium sulphate precipitate Signup and view all the answers

In the context of a 4-day old premature infant, what skin condition is suggested by the mother's complaint?

Jaundice Signup and view all the answers

What symptom is the infant presented with that indicates a possible concern regarding bilirubin levels?

Yellowish discoloration of the skin Signup and view all the answers

Why is it important to identify bilirubin levels in the urine of a premature infant?

To evaluate liver functionality Signup and view all the answers

Which amino acids are primarily detected using the xanthoproteic test?

Tyrosine and Tryptophan Signup and view all the answers

What is the color change observed in the xanthoproteic test when alkali is added to the nitro derivatives?

From yellow to orange Signup and view all the answers

What concentration of NaOH solution is used in the preparation for the xanthoproteic test?

40% Signup and view all the answers

Which reagent is used alongside heating in the xanthoproteic test to create yellow color nitro derivatives?

Concentrated nitric acid Signup and view all the answers

What is the main purpose of the xanthoproteic test?

To differentiate aromatic amino acids from non-aromatic ones Signup and view all the answers

What happens to coagulable protein when heated at isoelectric pH according to the method described?

It irreversibly uncurls and peptide bonds break down Signup and view all the answers

Which of the following materials is NOT required for conducting the xanthoproteic test?

Ultrasonic cleaner Signup and view all the answers

What is the resulting color of the solution after the xanthoproteic test when positive for aromatic amino acids?

Yellow Signup and view all the answers

What is the most likely diagnosis for the infant described in the case?

Physiologic jaundice Signup and view all the answers

What observation was noted in the infant's physical examination?

Good suck reflex Signup and view all the answers

What mechanism is suggested to explain the jaundice observed in the infant?

Decreased activity of Beta glucuronidase Signup and view all the answers

How did the jaundice progress in the infant over time?

It progressed to the upper chest area Signup and view all the answers

What advice would be given to the mother regarding the infant's condition?

Reassurance and continued monitoring Signup and view all the answers

What symptom was NOT observed during the infant's physical examination?

Abdominal enlargement Signup and view all the answers

What is a potential consequence of decreased Beta glucuronidase in terms of bilirubin levels?

Lower levels of conjugated bilirubin Signup and view all the answers

Which of the following findings is characteristic of physiologic jaundice in newborns?

Typically resolves without intervention Signup and view all the answers

Which statement is true regarding the activity of δ-aminolevulinic acid synthase in the liver?

It is typically decreased in individuals treated with barbiturates such as phenobarbital. Signup and view all the answers

What does the catabolism of hemoglobin primarily involve?

The oxidative cleavage of the porphyrin ring. Signup and view all the answers

What is a key product formed during the catabolism of hemoglobin?

Biliverdin. Signup and view all the answers

Which of the following statements is true about the transport of urobilin?

Urobilin appears as a result of hemoglobin degradation. Signup and view all the answers

Which heavy metal ion is known to strongly inhibit the activity of δ-aminolevulinic acid synthase?

Lead. Signup and view all the answers

Which of the following is a symptom that could be explained by issues related to porphyrin metabolism?

Painful blisters on sun-exposed areas. Signup and view all the answers

Which role does biotin play in the body concerning amino acids?

It facilitates the conversion of certain amino acids to specialized products. Signup and view all the answers

What is a common effect of increased levels of heavy metals in the body on enzyme activity?

Inhibits critical enzyme functions like δ-aminolevulinic acid synthase. Signup and view all the answers

What characterizes physiologic jaundice in newborns?

Onset after 24 hours of life Signup and view all the answers

What might indicate pathologic jaundice in a newborn?

Onset of jaundice within 24 hours of life Signup and view all the answers

Which of the following is associated with kernicterus?

Deposition of bilirubin in the basal ganglia Signup and view all the answers

What is the gold standard for diagnosing bilirubin levels in newborns?

Transcutaneous bilirubin measurement Signup and view all the answers

What total bilirubin level defines the threshold for pathologic jaundice?

12 mg/dL or greater Signup and view all the answers

Which clinical manifestation is NOT typically associated with jaundice in newborns?

Enhanced feeding ability Signup and view all the answers

What may cause an increase in unconjugated bilirubin levels in newborns?

Hemolysis Signup and view all the answers

Which of the following statements about bilirubin levels in newborns is TRUE?

Kernicterus can result from bilirubin levels around 30 mg/dL. Signup and view all the answers

Study Notes

Xanthoproteic Test

Detects aromatic amino acids, specifically Tyrosine and Tryptophan.
Heated protein solution with concentrated HNO3 produces yellow-colored nitro derivatives.
Differentiates aromatic amino acids that yield positive results from non-aromatic amino acids.

Materials Required

Bunsen burner
Test tubes
Distilled water
Concentrated HNO3
40% NaOH solution (prepared as 40g NaOH in 100mL distilled water)

Methodology

Add 1 mL of the test solution to a test tube.
Boil the mixture and observe the resulting color change.

Fouchet's Test

Oxidizing reagent for detecting bilirubin in urine.
Barium chloride precipitates sulfate radicals as barium sulfate.
Presence of bile pigments leads to adsorption on barium sulfate; oxidized by ferric chloride to form green biliverdin.

Clinical Application

Case study of a premature infant presenting with jaundice.
Diagnosis: Physiologic jaundice due to decreased beta-glucuronidase and lower conjugated bilirubin.
Monitoring and reassurance advised to the mother due to the typical progression of physiologic jaundice.

Jaundice Characteristics

Physiologic jaundice:
- Appears after 24 hours of life, resolves by 2 weeks.
- Characterized by increased unconjugated bilirubin, total levels ≤ 12mg/dL.
Pathologic jaundice:
- Onset < 24 hours or > 2 weeks.
- May show increased bilirubin and possibly serious symptoms.

Clinical Manifestations of Jaundice

Yellowish skin discoloration.
Poor suck reflex.
Kernicterus:
- Bilirubin deposition affects basal ganglia, leading to permanent damage.
- Symptoms include lethargy and seizures at bilirubin levels ~30mg/dL.

Diagnostic Measures

Gold standard: Transcutaneous bilirubin measurement.
Kramer scoring for visual estimation of jaundice severity.

Biochemical Insights

δ-Aminolevulinic acid synthase
- Activity decreased with drugs like phenobarbital.
- Catalyzes rate-limiting steps in porphyrin biosynthesis, requiring biotin.
- Inhibited by heavy metals (e.g., lead).
Hemoglobin catabolism
- Occurs in red blood cells.
- Involves oxidative cleavage of the porphyrin ring, producing bilirubin.

Patient Case Insights

50-year-old male with blisters on hands post-golfing suggests possible photosensitivity or dermatological conditions linked to porphyrin metabolism.

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Description

This quiz covers the Xanthoproteic and Fouchet's tests, focusing on their methodologies and clinical applications. Understand how these tests are used to detect specific amino acids and bilirubin, respectively. Test your knowledge of the materials and processes involved in these important biochemical analyses.