Serum lactate dehydrogenase is incorporated into both the International Prognostic Index for non-Hodgkin lymphoma and the staging of testicular germ cell tumours. Its usefulness in these settings rests on the fact that LDH:

• A Correlates specifically with bone marrow infiltration
• B Is specific to lymphoid tissue because lymphocytes express only the LDH-1 isoenzyme
• C Rises exclusively when tumour invades the liver parenchyma
• D Is released by tumour cells in proportion to total tumour burden and turnover rate ✓

Explanation

LDH is a nonspecific but sensitive index of cellular mass and rapid cell turnover, so elevated levels reflect bulky disease and predict poor prognosis in aggressive lymphomas and serve as a stage marker in germ cell tumours. Option B fails because all five LDH isoenzymes are widely distributed across tissues; heart and erythrocytes dominate LDH-1, not lymphocytes. Hepatic involvement is not required for LDH elevation, and bone marrow invasion is better assessed histologically than biochemically.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.