Q.26 Gmelin’s test and Van den Bergh reaction are used for :
I. identification of bilimbin in serum and urine. respectively.
2. identification of in serum only,
3. identification of bilimbin in urine only.
4. identification of bilimbin in urine and serum, respectively.
Gmelin’s test and Van den Bergh reaction are used for identification of bilirubin in serum and urine, respectively. The correct answer is option 4.
Option Analysis
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Option 1: Identification of bilirubin in serum and urine, respectively. Incorrect. This reverses the standard uses: Gmelin’s test detects bile pigments (primarily bilirubin) in urine via nitric acid color rings, while Van den Bergh detects bilirubin types (direct/indirect) specifically in serum.
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Option 2: Identification of bilirubin in serum only. Incorrect. Gmelin’s test is urine-specific for qualitative bile pigment detection (yellow-red-green rings from oxidation); Van den Bergh is serum quantitative/colorimetric for conjugated/unconjugated bilirubin.
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Option 3: Identification of bilirubin in urine only. Incorrect. Van den Bergh requires serum to differentiate direct (conjugated, soluble) vs. indirect (unconjugated) bilirubin via diazotization reaction; not adapted for urine.
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Option 4: Identification of bilirubin in urine and serum, respectively. Correct. Gmelin’s test (HNO₃ layered on urine) shows multicolored rings for urinary bilirubin in jaundice; Van den Bergh (serum + diazo reagent) yields pink/red for direct bilirubin or after alcohol for total.
Introduction to Bilirubin Tests
Gmelin’s test and Van den Bergh reaction identify bilirubin in urine and serum respectively, crucial for diagnosing jaundice types (obstructive vs. hemolytic). Gmelin’s detects conjugated bilirubin spillover into urine; Van den Bergh quantifies serum fractions—essential for pathology exams.
Test Mechanisms
Gmelin’s: Layer urine on conc. HNO₃; bile pigments oxidize forming yellow-red-blue-green rings at interface (positive in obstructive jaundice). Van den Bergh: Serum + diazotized sulfanilic acid; direct bilirubin reacts immediately (pink), indirect needs accelerator like alcohol.
| Test | Sample | Principle | Positive Indication |
|---|---|---|---|
| Gmelin’s | Urine | Nitric acid oxidation rings | Obstructive jaundice, conjugated bilirubin |
| Van den Bergh | Serum | Diazotization color | Direct (conjugated) pink; indirect after ethanol |
Clinical Relevance
Used together: High urine Gmelin + direct serum Van den Bergh suggests liver obstruction; indirect rise indicates hemolysis. Sensitivity limits (Gmelin qualitative) make them adjunct to modern assays in exams.
