ICD Coding for Elevated AST/ALT
The ICD-10 code for elevated AST/ALT is R74.0 (Nonspecific elevation of levels of transaminase and lactic acid dehydrogenase [LDH]).
Primary ICD-10 Code
- R74.0 is the specific code used for elevated transaminases (AST/ALT) when no underlying liver disease has been definitively diagnosed 1
- This code captures "nonspecific elevation of levels of transaminase" and is appropriate for initial documentation of elevated liver enzymes 1
Alternative Coding Considerations
- If a specific underlying cause has been identified, code the underlying condition instead of R74.0:
- K76.0 for fatty liver disease (NAFLD), which is the most common cause of isolated ALT elevation with prevalence of 20-30% in the general population 2
- K70.x series for alcoholic liver disease, particularly when AST/ALT ratio is >2:1 3, 2
- B18.x series for chronic viral hepatitis when serologies confirm the diagnosis 1
- K71.x series for drug-induced liver injury when medication causality is established 1
Clinical Context for Coding
- ALT is more liver-specific than AST, which can be elevated from cardiac muscle, skeletal muscle, kidney, or red blood cell disorders 1
- Normal ALT ranges are 29-33 IU/L for males and 19-25 IU/L for females, and elevations are classified as mild (<5× upper limit of normal), moderate (5-10× ULN), or severe (>10× ULN) 1, 2
- The AST/ALT ratio provides diagnostic clues: ratios >2 suggest alcoholic liver disease, while ratios <1 are characteristic of NAFLD or viral hepatitis 3, 1
Documentation Requirements
- When using R74.0, document the specific AST and ALT values, the degree of elevation, and any associated findings to support medical necessity for further evaluation 1
- If transaminase elevation persists for ≥6 months without identified cause, consider more specific coding based on imaging findings (such as hepatic steatosis on ultrasound) or biopsy results 1