Differential Diagnosis for Elevated LDH

Elevated lactate dehydrogenase (LDH) is a nonspecific marker that can be increased in a variety of conditions. Here's a categorized differential diagnosis:

• Single Most Likely Diagnosis

  • Hemolysis: Elevated LDH is commonly seen in hemolytic anemias due to the release of LDH from lysed red blood cells. Conditions such as autoimmune hemolytic anemia, hereditary spherocytosis, or glucose-6-phosphate dehydrogenase (G6PD) deficiency can lead to increased LDH levels.

• Other Likely Diagnoses

  • Malignancies: Certain cancers, especially lymphomas and leukemias, can cause elevated LDH due to tumor cell turnover and necrosis. Small cell lung cancer and testicular cancer are also known to have high LDH levels.
  • Tissue Injury: Myocardial infarction, liver disease, and skeletal muscle injury can all lead to elevated LDH due to the release of the enzyme from damaged cells.
  • Pulmonary Embolism: High LDH levels can be seen in pulmonary embolism, possibly due to the infarction of lung tissue.

• Do Not Miss Diagnoses

  • Pheochromocytoma: Although rare, pheochromocytomas can cause elevated LDH, and missing this diagnosis can be life-threatening due to the potential for hypertensive crises.
  • Testicular Cancer: Elevated LDH is a poor prognostic marker in testicular cancer, and early detection is crucial for treatment outcomes.
  • Severe Sepsis or Septic Shock: In the context of sepsis, elevated LDH can indicate tissue hypoxia and necrosis, which are critical conditions requiring prompt intervention.

• Rare Diagnoses

  • Germ Cell Tumors: Some germ cell tumors, aside from testicular cancer, can also present with elevated LDH.
  • Lymphangioleiomyomatosis: A rare lung disease that can cause elevated LDH due to the proliferation of smooth muscle-like cells in the lungs.
  • Gaucher's Disease: A genetic disorder that can lead to elevated LDH due to the accumulation of glucocerebroside in cells, particularly in the spleen, liver, and bone marrow.