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Tareq Abadl on CAD: A Practical Guide to Suspicion, Confirmation, and Correction in the Lab

Dr. Tareq Abadl / LinkedIn

Dec 11, 2025, 03:05

Tareq Abadl on CAD: A Practical Guide to Suspicion, Confirmation, and Correction in the Lab

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

“Cold Agglutinin Disease – What You Should Know

With winter coming, here’s an important lab concept: Cold Agglutinin Disease (CAD).

What Happens?

In this condition, IgM antibodies become active at low temperatures.
Because IgM has 5 arms (pentamer), it can bind to many RBCs at once → causing agglutination/clumping of red blood cells.

How Do You Suspect It in CBC?

You’ll notice something strange:

Hemoglobin (Hb): Usually normal

MCV: Normal

MCH: High

MCHC: High

This unusual pattern should raise suspicion.

The Deciding Test?

Blood Film (Peripheral Smear)

Under the microscope you will typically see:
RBC Agglutination
This confirms the cause of the abnormal indices.

What About Hematocrit?

Using the simple calculation:
Hematocrit ≈ Hb × 3
You will find that the calculated hematocrit looks normal
— another clue pointing to cold agglutination interfering with automated counting.

How to Handle the Sample?

To fix the problem in the lab:

Warm the blood sample at 37°C before running CBC

After warming, results return to normal and reliable

Tip:
In cold weather, it’s a good practice to warm any CBC sample if results look inconsistent.”

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