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Tareq Abadl: Differentiating Cold Agglutination from Hemolysis
Tareq Abadl/LinkedIn
Mar 11, 2026, 13:33

Tareq Abadl: Differentiating Cold Agglutination from Hemolysis

Tareq Abadl, Medical Laboratory Specialist and Director of the Blood Bank at Dr. Abdelkader Al-Mutawakkil Hospital, shared a post on LinkedIn:

“Differentiating Cold Agglutination from Hemolysis.

 1.Cold Agglutination

Cold agglutination is commonly associated with Cold Agglutinin Disease, a type of autoimmune hemolytic anemia caused by IgM antibodies that bind to red blood cells (RBCs) at low temperatures, leading to RBC clumping.

Specimen Appearance

  • EDTA blood shows a granular or clumping appearance
  • After centrifugation, the plasma remains clear and normal (not red)

CBC Findings

  • Decreased RBC count (falsely low)
  • Decreased hematocrit (Hct)
  • Hemoglobin (Hb) remains normal or near normal
  • Hb and Hct are inconsistent
  • MCV falsely increased
  • MCHC falsely increased

Cause: The analyzer counts clumped RBCs as a single cell, producing erroneous results.

Blood Smear Findings

  • RBCs appear in irregular clumps (agglutination)

Confirmation Test

  • Warm the specimen at 37°C for 15–30 minutes

Re-analyze CBC:

  • CBC parameters return closer to normal
  • RBC clumping disappears on smear

 2.Hemolysis

Hemolysis refers to the destruction of RBCs and can occur in vitro (in the tube) or in vivo (in the patient).

A. In Vitro Hemolysis (Specimen Hemolysis)

Specimen Appearance

  • Plasma appears clear red after centrifugation (hemolyzed plasma)
  • No granular or clumping appearance

CBC Findings

  • Hb may decrease slightly
  • Hct decreases proportionally
  • Hb and Hct remain consistent

Blood Smear

  • May see ghost cells
  • No agglutination

B. In Vivo Hemolysis

Commonly seen in conditions such as:

  • Autoimmune hemolytic anemia
  • G6PD deficiency
  • Thalassemia

Plasma Findings

  • Plasma may appear pink
  • Increased bilirubin
  • Increased LDH
  • Decreased haptoglobin

Blood Smear Findings

  • Spherocytes – autoimmune hemolytic anemia
  • Bite cells – G6PD deficiency
  • Schistocytes – fragmentation hemolysis

Key Laboratory Points (Very Important)

Suspect Cold Agglutination if:

  • Granular/clumping blood appearance
  • Hb and Hct are inconsistent
  • Markedly high MCHC (more than 36–37 g/dL)

Action:

  • Warm the sample at 37 degrees Celsius and repeat CBC

Suspect Hemolysis if:

  • Plasma is red after centrifugation
  • Hb and Hct remain consistent
  • No RBC clumping on smear”

Tareq Abadl

More posts featuring Tareq Abadl on Hemostasis Today. 

Cold Agglutination Cold Agglutinin Disease Health Hematology hemolysis Hemostasis Hemostasis News Hemostasis Today Medicine RBC 𝗿𝗲𝗱 𝗯𝗹𝗼𝗼𝗱 𝗰𝗲𝗹𝗹𝘀 Tareq Abadl
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