LDH is NOT a Reliable or Specific Marker for Liver Function Assessment
LDH is a nonspecific marker of tissue damage that can be elevated in liver disease, but it should NOT be used as a primary test for assessing liver function or diagnosing hepatic disease. 1, 2
Why LDH is Inadequate for Liver Testing
Lack of Specificity
- LDH elevation reflects tissue damage or increased cellular turnover from numerous conditions including hemolysis, myocardial infarction, kidney disease, muscle damage, infections, and malignancies—not just liver disease 2, 3
- For any given degree of liver injury, LDH provides no diagnostic advantage over standard liver function tests (aminotransferases, bilirubin, alkaline phosphatase) 1
Limited Diagnostic Value in Hepatic Disease
- While LDH can be elevated in liver disease, it is mentioned only as an optional test in tumor lysis syndrome panels or as part of broader metabolic assessments—never as a primary liver function marker 1
- Standard liver function tests (ALT, AST, alkaline phosphatase, GGT, bilirubin) are far superior for detecting and characterizing hepatic dysfunction 1
When LDH Has Clinical Utility in Hepatic Contexts
Differentiating Acute Liver Injury Patterns
- The ALT/LD ratio can distinguish viral hepatitis from ischemic hepatitis or acetaminophen toxicity: 4
- Viral hepatitis: ALT/LD ratio = 4.65 (LD relatively low)
- Ischemic hepatitis: ALT/LD ratio = 0.87 (LD markedly elevated)
- Acetaminophen injury: ALT/LD ratio = 1.46 (LD moderately elevated)
- An ALT/LD ratio >1.5 differentiates viral hepatitis from ischemic/toxic injury with 94% sensitivity and 84% specificity 4
Specific Pregnancy-Related Liver Conditions
- In HELLP syndrome (Hemolysis, Elevated Liver enzymes, Low Platelets), LDH elevation is part of the diagnostic criteria alongside hemolysis markers and thrombocytopenia 1
- In acute fatty liver of pregnancy (AFLP), elevated LDH (>42 IU/L by Swansea criteria) supports diagnosis but is nonspecific 1
Peritoneal Fluid Analysis
- In suspected secondary peritonitis from perforated viscus, ascitic LDH levels higher than serum LDH suggest this diagnosis 2
Proper Liver Function Assessment
Standard First-Line Tests 1
- Aminotransferases (ALT, AST): Primary markers of hepatocellular injury
- Alkaline phosphatase (ALP) and GGT: Markers of cholestasis
- Bilirubin (total and direct): Measures hepatic excretory function
- Albumin and INR: Assess synthetic liver function
- Complete blood count and platelet count: Evaluate for complications
Risk Stratification in Specific Contexts
- For NAFLD: Use FIB-4 or NAFLD Fibrosis Score, not LDH 1
- For alcohol-related liver disease: Use Fibroscan/ARFI elastography for fibrosis assessment 1
Critical Pitfalls to Avoid
- Do not order LDH as a routine liver function test—it adds no diagnostic value and may lead to unnecessary workup of nonspecific elevations 1, 2
- Do not interpret isolated LDH elevation as indicating liver disease without considering the numerous other causes (hemolysis, malignancy, myocardial infarction, etc.) 2, 3
- Hemolyzed blood samples falsely elevate LDH—always verify specimen quality before interpreting results 3
- Very high isolated LDH (>800 IU/L) is more commonly associated with malignancy (27% of cases) or infection (57% of cases) than primary liver disease 5
When to Consider LDH in Hepatic Evaluation
- Only when differentiating acute hepatocellular injury patterns (viral vs. ischemic vs. toxic) using the ALT/LD ratio 4
- In pregnancy with suspected HELLP syndrome or AFLP, as part of comprehensive evaluation 1
- When evaluating ascitic fluid in suspected peritonitis 2
- Never as a standalone or primary liver function marker 1, 2