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Liver function tests
From WikEM
(Redirected from LFTs)
Contents
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
