Bilirubin and Jaundice
Bilirubin and Jaundice
Unconjugated hyperbilirubinaemia
- Pre-hepatic (acholuric)
- Hepatocellular
Conjugated hyperbilirubinaemia
- Hepatocellular
- Intrahepatic obstruction
- Extrahepatic obstruction
Note:
- <20% of bilirubin conjugated = Unconjugated hyperbilirubinaemia
- >50% of bilirubin conjugated = Conjugated hyperbilirubinaemia
Unconjugated hyperbilirubinaemia
Classification:
- Pre-hepatic (acholuric) (vast majority. Secondary to increased bilirubin production
- Hepatocellular. Secondary to reduced hepatocyte uptake of bilirubin.
Cause:
- Haemolysis (must be 2 x normal to be significant) – Rarely causes rise over 70 micromol/L
- haemolytic anaemia
- erythroblastosis foetalis
- pernicious of prematurity
- Congenital
- Gilbert disease (GD)
- Crigler-Najjar syndrome (CS)
- Iatrogenic
- Drugs: chloramphenicol, gentamicin, pregnanediol
- Physiological
- Neonatal jaundice and Breast-milk jaundice
Conjugated hyperbilirubinaemia
- Hepatocellular – Diminished hepatocyte function. If severe can be associated with unconjugated hyperbilirubinemia due to total inability to conjugate bilirubin
- hepatitis – Viral, toxic, alcoholic, autoimmune
- cirrhosis
- leptospirosis
- Drugs
- liver parenchymal injury (toxic hepatitis)
- halothane, paracetamol, methyldopa, phenytoin, barbiturates, MAOI, sulphonamides
- Intrahepatic obstruction (hepatic canalicular disorders)
- Hepatitis (viral)
- Cirrhosis (Primary biliary cirrhosis)
- Intrahepatic cholestasis
- Drugs
- indomethacin, erythromycin
- chlorpromazine, isoniazid, flucloxacillin, OCP
- Congenital
- Dubin–Johnson syndrome
- Rotor syndrome
- Extrahepatic obstruction
- Calculi, tumour, scar tissue in common bile duct or hepatic excretory duct
- Gallstones, carcinoma of head of pancreas and lymphoma with extrinsic nodal compression of the porta hepatis are commonest
Serum Bilirubin
Measures unconjugated and conjugated (Normal range: 6-24 micromol/L). Initial result details TOTAL bilirubin measured
- Clinically detectable jaundice
- Conjugated hyperbilirubinaemia – 35 micromol/L
- Unconjugated hyperbilirubinaemia – 45 micromol/L
- Ratio of unconjugated and conjugated helps to determine cause of hyperbilirubinaemia
- Predominantly unconjugated (<20% bilirubin conjugated)
- Predominantly conjugated (>50% bilirubin conjugated)
Urine Bilirubin
Ward Test Urine (WTU) or laboratory for may assess urine for Urine bilirubin and Urine urobilinogen
Urine bilirubin:
- Conjugated bilirubin excreted into GIT is reabsorbed in very small amounts
- Kidneys filter soluble form and it appears in urine
- Bilirubin is NOT normally present in urine
- Urine -dark in colour, usually brown with yellow foam
- Presence of bilirubin implies Conjugated hyperbilirubinemia
Urine urobilinogen:
- Normal: 1-4mg/day (compared to 250mg in stool)
- Absence of urobilinogen
- Conjugated – Complete extrahepatic obstruction or Broad spectrum antibiotics destroying intestinal flora
- Low levels of urobilinogen
- Unconjugated – Congenital (Crigler-Najjar syndrome, Gilbert syndrome)
- Conjugated – Complete extrahepatic obstruction
- Increased levels
- Unconjugated – haemolysis, highly alkaline urine or eating bananas up to 48 hours before test
Critical Care
Compendium
Associate Professor Curtin Medical School, Curtin University. Emergency physician MA (Oxon) MBChB (Edin) FACEM FFSEM Sir Charles Gairdner Hospital. Passion for rugby; medical history; medical education; and asynchronous learning #FOAMed evangelist. Co-founder and CTO of Life in the Fast lane | Eponyms | Books | Twitter |