High lactate dehydrogenase (LDH) suggests tissue damage or cell breakdown. It can be raised with hemolysis, heart attack, liver disease, infections, inflammation, and some cancers. A high LDH alone doesn’t pinpoint the cause; doctors use other blood tests, imaging and clinical findings to locate the source and monitor severity. Treatment targets the underlying condition; LDH trends help assess response.

The serum lactate dehydrogenase (LDH) test measures an enzyme released when cells are damaged. It’s used as a non‑specific marker to detect and monitor tissue injury from causes such as hemolysis, liver or muscle disease, heart attack, infections, pulmonary embolism, and some cancers. Elevated levels help assess severity, follow disease progression or treatment response, and are interpreted alongside other specific tests.

High lactate dehydrogenase (LDH) in cancer usually reflects increased tumor cell turnover, tissue breakdown, hypoxia and higher tumor burden. It is a nonspecific marker associated with more aggressive disease, greater likelihood of metastasis and poorer prognosis. Clinicians use LDH trends to help stage disease and monitor treatment response, but elevations can also result from non-cancer causes (liver disease, hemolysis, infection), so context matters.

High serum LDH is a marker, not a disease; treatment targets the underlying cause. Management includes diagnosing the source (blood tests, imaging) and treating it—e.g., reperfusion for heart attack, antibiotics for infection, steroids or transfusion for hemolysis, fluids and electrolyte management for rhabdomyolysis, or cancer-directed therapy. Stop offending drugs, give supportive care, and monitor LDH and clinical response.

Elevated LDH is a nonspecific marker of tissue injury and is often seen with infections—particularly severe or systemic ones. Common examples include viral infections (e.g., COVID-19, infectious mononucleosis/EBV), bacterial sepsis and severe pneumonia, fungal infections like Pneumocystis jirovecii, and parasitic infections such as malaria. It indicates cell damage rather than a specific pathogen; clinical context and other tests are required.

Stress can indirectly raise lactate dehydrogenase (LDH) when it leads to tissue damage, intense exercise, hypoxia, inflammation, infection, or severe physiological stress (e.g., sepsis, heart injury). Pure psychological stress alone is unlikely to markedly elevate LDH, though chronic stress–related inflammation or harmful behaviors (overexertion, alcohol use) may contribute. Elevated LDH requires medical evaluation to find the cause.