A young male presents with elevated bilirubin levels. Examination of urine shows presence of bilirubin while urobilonogen is absent. Likely diagnosis is:
Answer is C (Obstructive Jaundice) Presence of. Bilirubin in urine and absence of urinary urobilonogen suggests a diagnosis of obstructive jaundice. Pathophysiology of different types of jaundice Normal blood contains unconjugated bilirubin only (no conjugated bilirubin) Unconjugated bilintbin is water insoluble (lipophilic, lipid soluble) and not filterable by the kidney. Unconjugated bilirubin is taken up from the systemic circulation by hepatocytes (1) Unconjugated bilirubin is then conjugated to bilirubin glucoronide by glucorony I transferase within the hepatocytes(2) Conjugated bilirubin is then excreted into the bile from where it reaches the GIT (3) This is the rate limiting step. Conjugated bilirubin is water soluble and filterable by the kidney Normally, there is no conjugated bilirubin in the systemic circulation and hence no bilirubin is filtered in the kidney or present in the urine. Abnormally When there is hepatocellular dysfunction or bile flow is totally obstructed, conjugated bilirubin -leaks" into the systemic circulation This conjugated bilirubin may now be excreted by the kidney and be detected in urine. Bilirubin in urine (bilirubinurial Presence of bilirubin in urine suggests a diagnosis of conjugated hyperbilirubinemia either due to hepatocellular jaundice or obstructive jaundice. Within the GIT conjugated bilirubin is degraded/reduced to urobilinogen and then to stercobilinogen Urobilinogen is water soluble and filterable by the kidney Normally, a small poion of the urobilinogen is reabsorbed from the gut and excreted by the kidney (<4 mg/day) In non obstructive hyperbilirubinemia (hemolytic, hepatocellular) the amount of urobilinogen exreatcd by the kidney is increased as more urobilinogen is formed and reabsorbed. Elevated levels of urobilinogen suggest primarily an non obstructive hyperbilirubinemia In obstructive hyperbilirubinemia, conjugated bilirubin does not reach the GIT and hence no urobilinogen is formed Absent levels of urobilinogen suggest a diangnosis of obstructive hyperbilirubinentia Condition Serum Bilirubin Urine Urobilinogen Urine Bilirubin Fecal urobilinogen Normal Direct 0.1-0.4 mg/dl Indirect 0.2-0.7 mg/dl 0-4 mg/24 h Absent 40-280 mg/24h Hemolytic anemia T Indirect Increased Absent Increased Hepatitis "i' Direct and indirect Decreased if micro- obstruction is present Present if microobstruction occurs Decreased Obstructive jaundice T Direct Absent Present Trace to absent
Hepatitis
Hemolytic jaundice
Obstructive jaundice
Gilbe's syndrome