N2i: Describe the interpretation of lab assessment of liver function (albumin, glucose, bilirubin, coag profile, ammonia)

Clinical blood biochemistry can give info re: states of patient’s liver

Divided into:

Enzymes of Hepatocyte Integrity

AST/ALT – < 40IU/L

  • Enzymes of parenchymal cells
  • Used to assess cellular injury
  • ALT is more specific to liver tissue & less elevated with alcoholic hepatitis
  • AST:ALT > 2:1 → strongly suggest ETOH aetiology, especially if ↑GGT
  • ↑enzyme release with liver damage, but no correlation with disease severity
  • Not useful at determining liver function

Enzymes of Cholestasis

ALKP 30 – 120IU/L

  • Enzyme of cells lining bile ducts
  • Non-specific (i.e. found in bone)
  • ↑with biliary obstruction, ↑bone turnover (i.e. Paget’s disease)

GGT <50 IU/L

  • Enzyme lining biliary tract
  • Isolated ↑GGT = EtOH
  • ↑with biliary obstruction

Synthetic Liver Function

Albumin – Normal 29 – 58g/L

  • Protein synthesised exclusively by liver
  • T ½ 20 days
  • ∴not good indicator of acute hepatic dysfunction
  • Can also ↓ with malnutrition

Coagulation factors – Normal INR <1.3, PT 9.5 – 13.5 secs

  • All clotting factors except F VIII & vWF synthesised exclusively by liver
  • Rapid turnover → ∴good indicators of liver function
  • Must consider Vit K deficiency because liver disease will = ↓ ADEK absorption


  • ↓with severe liver dysfunction
  • Glycogen store, gluconeogenesis

Lipid profile

  • Elevate TAGS & lipoprotein with abnormal liver metabolism

Detoxification & Excretory Function

Bilirubin <1.5mg/dL

  • Breakdown product of heme metabolism
  • Liver conjugates (H2O solubility) → excreted in bile
  • Conjugated & unconjugated levels in bile & urine will indicate intrahepatic disease/post-hepatic obs
  • Intrahepatic = ↓conjugated & ↑unconjugated plasma
  • Post-hepatic = ↑conjugated, ↑urobilinogen

NH3 – Normal <50µmol/L

  • Amino acid metabolism
  • Converted to urea by liver
  • ↑with liver failure


  • Test for specific causes of liver disease, including hepatitis serology, antimicrosomal antinuclear Ab, a-fetoprotein (hepatoma), Fe studies (haemochromatosis), ceruloplasmin (Wilson’s disease) & many others