Definition of Transaminitis
Transaminitis refers to elevated serum aminotransferases (ALT and AST) indicating hepatocellular injury, not actual liver function impairment. 1, 2
Core Terminology
The term "transaminitis" specifically describes inflammatory processes characterized by elevated alanine aminotransferase (ALT) and aspartate aminotransferase (AST), and should be reserved for conditions causing hepatocyte damage rather than cholestatic injury 2.
This terminology is distinct from "abnormal liver function tests," which specifically denote loss of synthetic function measured by serum albumin and prothrombin time, not enzyme elevations 2.
Transaminases are indicators of hepatocellular injury and necrosis caused by leakage of these enzymes from damaged liver cells into serum 3.
Normal Reference Ranges
Normal ALT levels are 29 to 33 IU/L (0.48-0.55 μkat/L) in men and 19 to 25 IU/L (0.32-0.42 μkat/L) in women 3, 4.
ALT is more specific for liver injury than AST due to low concentrations in skeletal muscle and kidney, whereas AST can be elevated from disorders involving heart, skeletal muscle, kidneys, brain, and red blood cells 3, 5.
Severity Grading System
The American Gastroenterological Association classifies transaminitis severity as follows 3, 1:
- Grade 1: AST/ALT > upper limit of normal (ULN) to 3.0× ULN (mild elevation)
- Grade 2: AST/ALT > 3.0 to 5.0× ULN (moderate elevation)
- Grade 3: AST/ALT > 5.0 to 20× ULN (severe elevation)
- Grade 4: AST/ALT > 20× ULN (life-threatening elevation)
Clinical Context
Transaminases are found in almost every organ, not exclusively the liver, making clinical context essential for interpretation 5.
Elevated transaminases reflect disturbed cell membrane permeability rather than measuring actual liver synthetic capacity 5.
The pattern of elevation matters diagnostically: AST:ALT ratio <1 suggests non-alcoholic fatty liver disease, while AST:ALT >1 may indicate advanced fibrosis or alcoholic liver disease 1.