Liver Functionality Test

• Alkaline Phosphatase (ALP)

  • Highly concentrated in the microvilli of the bile canaliculus, bones, intestines, placenta
  • 4 isoenzymes:

  1. ALPI: in intestines
  2. ALPL: in liver (bile ductular cells), bone, kidney
  3. ALPP: in placenta
  4. ALPG: in testicles & ovaries

  • Damage to the bile canaliculi/ Obstruction of bile flow (Cholestasis) --> increase serum ALPL + GGT + Bilirubin
  • Males & Females: similar level of ALP; decreases by age 20
• • increase TOTAL serum ALP not liver damage only
  • increase serum ALPL not liver damage only
• Gamma-Glutamyltransferase (GGT)

  • Located on membranes of cells w/ high secretory/ absorptive activities (e.g. hepatocytes)
  • Primary function: [catalyze transfer of gamma-glutamyl group (from peptides) --> other amino acid]
  • Abundant in many sources
• Gamma-Glutamyltransferase (GGT)

  • GGT more sensitive >> ALP (bc GGT increasw 12 - fold in obstructive liver disease compared to ALP [only 3 - fold increase])
  • Elevation of serum GGT levels:

  1. Liver damage: Hepatocytic death -- increase GGT, AST, ALT
  2. Biliary obstruction: Cholestasis -- increase serum GGT, ALP, Bilirubin; AST & ALT may not change

  3. Alcohol use: increase serum GGT; AST/ALT ration by > 2-fold

  • GGT: adult males > females; increase in levels overtime
• Bilirubin

  • End product of heme catabolism in the spleen; 80% derived from hemoglobin

  i) Unconjugated bilirubin --> transported to the liver (loosely bound to albumin; bc water- insoluble)

  ii) Conjugated bilirubin (soluble) --> excreted via urine and feaces

  • Cholestasis: increase serum bilirubin, GGT, ALP
• Bilirubinometer: used to non-invasively measure the color of the skin

  • use to screen for jaundice in new born