Physiological and Biochemical Basis of Hyperbilirubinemia

Hyperbilirubinemia refers to the elevated levels of bilirubin in the bloodstream, leading to jaundice. This condition is classified into unconjugated and conjugated hyperbilirubinemia, each with distinct pathophysiological mechanisms.

Unconjugated Hyperbilirubinemia

Pathophysiology

Unconjugated hyperbilirubinemia results from increased bilirubin production, decreased hepatic uptake, or impaired conjugation. Hemolysis, ineffective erythropoiesis, and Gilbert syndrome are common causes.

Clinical Implications

Excessive unconjugated bilirubin can lead to kernicterus in neonates, a severe neurological condition due to bilirubin deposition in the brain.

Conjugated Hyperbilirubinemia

Pathophysiology

Conjugated hyperbilirubinemia occurs due to biliary obstruction, hepatocellular damage, or impaired excretion. Conditions such as primary biliary cholangitis, Dubin-Johnson syndrome, and viral hepatitis contribute to this form.

Clinical Implications

Unlike unconjugated bilirubin, conjugated bilirubin is water-soluble and excreted in urine, often leading to dark-colored urine and pale stools.

Diagnosis and Management

• Laboratory tests (serum bilirubin levels, liver function tests)
• Imaging studies (ultrasound, MRI, cholangiography)
• Management focuses on addressing the underlying cause, including phototherapy for neonates and surgery for obstructive jaundice.

Conclusion

Understanding the physiological and biochemical basis of hyperbilirubinemia is essential for accurate diagnosis and effective treatment strategies. Early intervention can prevent complications and improve patient outcomes.