Differential Diagnosis for Normocytic Anemia with Elevated LDH

• Single Most Likely Diagnosis

  • Hemolytic anemia: This condition is characterized by the premature destruction of red blood cells, which can lead to normocytic anemia. Elevated LDH (lactate dehydrogenase) is a marker of hemolysis, as it is released from damaged red blood cells. The combination of normocytic anemia and elevated LDH strongly suggests a hemolytic process.

• Other Likely Diagnoses

  • Myeloproliferative neoplasms (e.g., polycythemia vera, essential thrombocythemia): These conditions can sometimes present with normocytic anemia due to ineffective erythropoiesis or other mechanisms, and elevated LDH can be seen due to increased cell turnover.
  • Myelodysplastic syndromes (MDS): MDS can cause normocytic anemia due to ineffective erythropoiesis, and elevated LDH may reflect the dysplastic process or associated hemolysis.
  • Chronic diseases (e.g., chronic kidney disease, chronic infections): While these conditions more commonly cause microcytic or normocytic anemia without significant LDH elevation, in some cases, especially with associated hemolysis or significant inflammation, LDH can be elevated.

• Do Not Miss Diagnoses

  • Paroxysmal Nocturnal Hemoglobinuria (PNH): A rare, acquired, life-threatening disease of the blood characterized by the destruction of red blood cells (hemolysis), bone marrow failure, and the potential for blood clot formation (thrombosis). Elevated LDH is a hallmark of intravascular hemolysis, which occurs in PNH.
  • Autoimmune hemolytic anemia (AIHA): This condition involves the immune system producing antibodies against the patient's own red blood cells, leading to their destruction. It can present with normocytic anemia and elevated LDH due to hemolysis.

• Rare Diagnoses

  • Wilson's disease: A genetic disorder that leads to copper accumulation in the body, which can cause hemolytic anemia among other symptoms. While rare, it's an important consideration in young patients with unexplained hemolytic anemia.
  • Thalassemia intermedia: Some forms of thalassemia can present with normocytic anemia and elevated LDH due to ineffective erythropoiesis and hemolysis, although this is less common.
  • Red cell membrane disorders (e.g., hereditary spherocytosis): These inherited conditions affect the red blood cell membrane, leading to hemolytic anemia. While they often present in childhood, some forms may not be diagnosed until adulthood.