Lactate Dehydrogenase (LDH) in Oncology
What is LDH?
- Intracellular enzyme involved in glycolysis (converts pyruvate ↔ lactate).
- Found in many tissues (muscle, liver, kidney, blood cells, etc.).
- Nonspecific marker → elevated when cells are lysed or turnover is high.
LDH is not a diagnostic test, but it is a prognostic and monitoring biomarker in several malignancies:
1. Hematologic Malignancies
- ALL, AML, Lymphomas (esp. Burkitt, DLBCL), CML blast crisis:
- High LDH = high tumor burden or rapid proliferation.
- Often correlates with risk of tumor lysis syndrome (TLS).
- NCCN/ASCO TLS guidelines: LDH > 2× ULN = intermediate/high TLS risk.
2. Solid Tumors
- Melanoma, testicular cancer, renal cell carcinoma, lung cancer, sarcomas:
- LDH is used as a prognostic biomarker.
- Example: In metastatic melanoma, high LDH = poor prognosis and influences staging (AJCC incorporates LDH in M1 sub-staging).
Clinical Uses in Oncology
| Use Case | Role of LDH |
|---|---|
| Prognosis | Elevated LDH often = aggressive disease, worse survival. |
| TLS risk stratification | LDH >2× ULN → higher risk, may need rasburicase instead of allopurinol. |
| Response monitoring | In lymphoma or germ cell tumors, falling LDH = treatment response. |
| Staging | Included in staging/prognosis models (e.g., IPI in NHL, AJCC in melanoma). |
Limitations
- Nonspecific → also elevated in hemolysis, liver disease, myocardial infarction, infection, or strenuous exercise.
- Must be interpreted in clinical context, not alone.
Oncology Pharmacy Pearls
- Always check baseline LDH in hematologic malignancies → helps TLS risk planning.
- For TLS prophylaxis: High LDH + high WBC/tumor burden → favor rasburicase over allopurinol.
- Monitor LDH alongside uric acid, K⁺, phosphate, calcium, creatinine when managing TLS.
- In metastatic melanoma or testicular cancer, persistently high LDH despite therapy = bad prognostic