Which parameter is NOT increased in hemolytic anemia: Serum/Plasma lactate dehydrogenase (LDH), Serum/Plasma haptoglobin, reticulocyte count, or indirect bilirubin?

Serum/Plasma Haptoglobin is NOT Increased in Hemolytic Anemia

In hemolytic anemia, serum/plasma haptoglobin is REDUCED, not increased, making option B the correct answer. 1

Laboratory Parameters in Hemolytic Anemia

Hemolytic anemia is characterized by premature destruction of red blood cells, resulting in specific laboratory abnormalities:

1. Serum/Plasma LDH (Lactate Dehydrogenase): INCREASED

   • Released from damaged red blood cells during hemolysis
   • Serves as a marker of cellular destruction 1, 2

2. Serum/Plasma Haptoglobin: DECREASED

   • Haptoglobin binds to free hemoglobin released during hemolysis
   • Rapid clearance of haptoglobin-hemoglobin complexes by the liver leads to reduced serum levels
   • Levels are often below detection limits in active hemolysis 1, 2

3. Reticulocyte Count: INCREASED

   • Represents bone marrow response to anemia
   • Indicates increased red blood cell production to compensate for hemolysis
   • Reticulocytosis is a hallmark finding in hemolytic anemias 1, 2

4. Indirect Bilirubin: INCREASED

   • Result of increased red cell breakdown and subsequent metabolism of hemoglobin
   • Contributes to jaundice seen in hemolytic states 1, 2

Clinical Significance

Understanding these laboratory parameters is crucial for:

• Diagnosing hemolytic anemia
• Distinguishing hemolytic from non-hemolytic causes of anemia
• Monitoring disease activity and response to treatment

In some cases of hemolytic anemia, such as autoimmune hemolytic anemia (AIHA), haptoglobin levels are characteristically reduced below detection limits, while other markers of hemolysis (LDH, reticulocyte count, indirect bilirubin) are elevated 3, 4.

Important Considerations

• Haptoglobin is an acute phase reactant and may be falsely normal in patients with concurrent inflammatory conditions despite ongoing hemolysis
• Recent blood transfusions generally do not significantly affect haptoglobin measurements, allowing its use in recently transfused patients 5
• In rare cases, LDH may be normal despite active hemolysis, making haptoglobin an even more important diagnostic marker 3

Therefore, among the options provided, serum/plasma haptoglobin (option B) is the parameter that is NOT increased in hemolytic anemia; rather, it is characteristically decreased.