Van den Bergh reaction

Van den Bergh reaction is a clinical test used in the diagnosis and monitoring of bilirubin metabolism disorders, including jaundice and diseases affecting the liver. This biochemical assay distinguishes between direct (conjugated) and indirect (unconjugated) bilirubin in a patient's blood serum, providing essential information about liver function, bile duct patency, and the presence of hemolytic diseases.

Background

Bilirubin is a yellow compound that occurs in the normal catabolic pathway that breaks down heme in vertebrates. Its levels in the blood can indicate the health of the liver and the biliary system. The Van den Bergh reaction, developed by Adrianus Van den Bergh and his colleagues in the early 20th century, is a cornerstone in understanding and diagnosing conditions related to bilirubin metabolism.

Procedure

The test involves adding a diazo reagent to a serum sample. The reagent reacts with direct bilirubin to produce a pink or red color almost immediately, known as the "direct" Van den Bergh reaction. If no color change occurs initially, alcohol is added to the mixture to facilitate the reaction of the diazo reagent with indirect bilirubin, resulting in a color change after some time. This is known as the "indirect" Van den Bergh reaction. The intensity of the color, which can be quantitatively measured, correlates with the concentration of bilirubin in the sample.

Clinical Significance

The Van den Bergh reaction is pivotal in differentiating between various types of jaundice:

• Pre-hepatic jaundice: Characterized by increased levels of indirect bilirubin due to excessive breakdown of red blood cells.
• Hepatic jaundice: Involves abnormalities in the liver, leading to elevated levels of both direct and indirect bilirubin.
• Post-hepatic jaundice: Caused by obstructions in the bile duct, resulting in increased levels of direct bilirubin.

Understanding the type of bilirubin that is elevated helps in pinpointing the underlying cause of jaundice and guiding treatment.

Limitations

While the Van den Bergh reaction is a valuable diagnostic tool, it has limitations. It can be influenced by the presence of certain drugs or substances in the blood that may interfere with the diazo reaction. Moreover, newer methods with higher sensitivity and specificity, such as high-performance liquid chromatography (HPLC), are gradually replacing the Van den Bergh reaction in clinical practice.

Conclusion

The Van den Bergh reaction remains a fundamental test in the field of medicine, especially in hepatology. Despite its limitations and the advent of more advanced techniques, it continues to be a useful initial screening tool for assessing bilirubin metabolism and liver function.