Liver function tests

Background

Normal Values

  • ALT: 7 - 55 U/L
  • AST: 8 - 48 U/L
  • Alk Phos: 45 - 115 U/L
  • Albumin: 3.5 to 5.0 g/dL
  • Total protein: 6.3 - 7.9 g/dL
  • Bilirubin: 0.1 - 1.2 mg/dL
  • GGT: 9 - 48 U/L
  • LDH: 122 - 222 U/L
  • PT: 11 - 14 seconds
  • PTT: 25 - 35 seconds
  • INR: 0.8 - 1.2

Albumin / Total Protein

Bilirubin

Aminotransferases (ALT/AST)

  • Elevation is associated with liver damage
  • Elevations in AST >> ALT suggest liver damage from alcoholism (i.e. alcoholic hepatitis)
  • Elevations in ALT >> AST suggest liver damage from another etiology (i.e. infectious hepatitis)

Alkaline Phosphatase

  • Predominantly found in the liver, bile ducts, kidney, and bones
  • Because of its abundant production in biliary duct tissue, elevation reflects a problem with biliary stasis or obstruction
    • Elevation may also occur in patients with increased bone turnover (e.g. 2/2 puberty, osteoporosis, hyperparathyroidism, Paget's disease, etc.)

Gamma-glutamyl Transferase (GGT)

  • Like alkaline phosphatase, also found in abundance in the liver and bile ducts (also spleen, heart, and brain)
  • Elevation in conjunction with an elevation in alkaline phosphatase, suggests biliary stasis/obstruction

Lactate Dehydrogenase (LDH)

  • Found in most body tissues
  • Elevation can occur as a result of cellular rupture (different isozymes can specify tissue type involved)
    • Cardiac - Demand ischemia, myocarditis
    • Pulmonary - pulmonary embolism
    • GI - hepatitis, small or large bowel obstruction
    • Hematologic - hemolytic process, ineffective erethropoiesis
    • Other - pregnancy, cancer, infection, systemic autoimmune disorders

See Also

References