Lactate Dehydrogenase (LDH)

Lactate dehydrogenase is an enzyme found inside almost every cell in the body that helps convert sugar into energy. When cells are damaged or dying, they release LDH into the blood or into body fluids like the fluid around the lungs, so doctors measure it as a general marker of tissue injury, inflammation, or tumor activity. It is not specific to any one disease, but elevated levels can signal that something is wrong and needs further investigation.

Origin

LDH was first described in the 1940s as part of the research into how cells generate energy without oxygen (anaerobic metabolism). The name comes from its biochemical role: it catalyzes the conversion between lactate and pyruvate. It entered routine clinical use in the 1950s and 1960s as laboratories developed reliable blood tests for enzyme activity.

Significance in Asbestos Context

For patients with pleural mesothelioma or asbestos-related pleural effusions, LDH is one of the first numbers doctors look at when analyzing fluid drained from around the lung (a thoracentesis sample). A high LDH level in pleural fluid, especially compared to the blood level, helps classify the fluid as an "exudate", the type seen with cancer, infection, or significant inflammation, rather than simple fluid buildup from heart failure. LDH is also used to track how mesothelioma is responding to chemotherapy: rising levels can suggest the cancer is progressing, while falling levels may indicate treatment is working. It is part of several prognostic scoring systems for mesothelioma, including the EORTC and CALGB scores, where elevated LDH is associated with shorter survival. Because LDH appears throughout your medical records (in lab reports, oncology notes, and imaging correlations), it may be referenced by the medical experts who review your case.

Example Sentence

The oncologist explained that the patient's rising LDH, combined with new findings on the CT scan, suggested the mesothelioma was no longer responding to first-line chemotherapy.

Related Terms

Pleural Effusion, Thoracentesis, Light's Criteria, Exudate, Mesothelioma, EORTC Prognostic Score

Notes

• Ask your oncologist whether your baseline LDH was measured before treatment started, and request that it be tracked at each follow-up so trends are visible over time.
• If you have had a thoracentesis, request a copy of the pleural fluid analysis. The LDH value and the fluid-to-serum LDH ratio are key parts of the report and are often cited in expert medical opinions.
• Keep copies of all lab reports showing LDH values; these create a timeline of disease activity that can support both medical decision-making and documentation of disease progression in a legal claim.
• Remember that LDH can rise for reasons unrelated to mesothelioma, including muscle injury, recent blood draws with hemolysis, liver problems, or certain medications. Ask your doctor to interpret values in context rather than reacting to a single number.