Be informed

When you understand what’s happening in your body, you can be more comfortable talking to your doctor about it. You probably know all about sickle-shaped red blood cells, but did you know that sickle cell disease actually makes your blood "sticky"? Keep reading to find out more.

Why is hemoglobin so important?

Hemoglobin is a protein in red blood cells that helps carry oxygen through the body. However, if someone inherits an abnormal hemoglobin gene from a birth parent, then their hemoglobin may not work the way it is supposed to. Sickle hemoglobin, HbS, causes red blood cells to become stiff and sickle shaped. This affects how healthy blood flow can be.

Normal red blood cells

Normal red blood cells look like discs. The disc shape helps red blood cells squeeze through small blood vessels without being damaged. By keeping their healthy disc shape, red blood cells can carry oxygen through the body.

Sickle red blood cells

Sickled red blood cells are abnormal and unstable.
The sickle-shaped cells are stiff, which makes it hard for them to squeeze through small blood vessels without bursting.


Hemolysis of red blood cells

The breaking apart of red blood cells is called hemolysis [hi-mol-uh-sis]. While hemolysis is normal (everyone’s red blood cells break apart in time), it happens more quickly and more often in people who have sickle cell disease.

A red blood cell that is disc shaped can live in the bloodstream for up to 4 months. A sickled red blood cell, however, can break apart in fewer than 3 weeks.


Blood cells affected with anemia

The body tries to make new red blood cells to replace the ones that break apart. Unfortunately, it is hard for the body to produce new blood cells fast enough. That creates a problem called anemia [uh-nee-mee-uh], which makes peope feel weak and tired. When anemia is severe, blood transfusions may be necessary.

Sickle cell disease makes blood "sticky"

Sickle cell disease goes beyond red blood cells. The disease has a silent, ongoing effect on blood vessels and other blood cells and platelets, too. Read on to find out more.


Image of “sticky” blood cells in sickle cell disease

1. Stickiness

From an early age, SCD starts to damage and inflame the blood vessels. Damaged blood vessels become irritated and activate molecules in the blood called selectins [si-lekt-ins]. You can think of selectins as “sticky factors.” These sticky factors are what cause blood cells to stick to blood vessel walls and to each other.


Clusters form in bloodstream in sickle cell disease
Clusters can form

2. Clusters

As more and more blood cells get sticky, the cells get stuck to each other and to the vessel walls. This process can form clusters in the bloodstream. A doctor may call this "multicellular adhesion."


Reduced of blocked blood and oxygen flow caused by clusters in sickle cell disease
Blood flow slows down or is blocked

3. Blockages

The clusters build up and become blockages, making it difficult for blood and oxygen to flow normally in the vessels. This process of clusters forming and becoming blockages is ongoing. A doctor may call this "vaso-occlusion" [vey-soh uh-kloo-zhun].


Vaso-occlusion, pain crisis, and organ damage in sickle cell disease
Vaso-occlusion, pain crises, and organ damage

4. Pain Crises

When blood cell clusters get big enough, they can cause episodes of sudden, unpredictable, and intense pain called pain crises. A doctor may refer to pain crises as "vaso-occlusive crises" [vey‑soh uh‑kloo‑siv kri‑seez].

Pain crises can come on without warning and may require medical help. Also, when blood flow slows or gets blocked (vaso-occlusion), there can be more health risks over time, like organ damage and organ failure.

How sickle cell disease may affect health

Sickle cell disease has the potential for a widespread impact on the body and mind, and overall health.

The impact can be short-lived such as the pain of a pain crisis or associated with acute and chronic complications such as organ damage and organ failure.

Below, you'll find some of the more common health problems associated with sickle cell disease. To help you talk to a doctor, each problem is labeled with the term you might recognize (in black) and the term a doctor might use instead (in orange).



What are possible health effects for trait carriers?

Sickle cell trait carriers may face fewer and less severe health complications. They may not experience any complications.

A sickle cell trait carrier may be at increased risk for:

  • Kidney cysts (saclike buildup of fluid)
  • A blood clot in the lungs
  • Heat stroke
  • Damage to the spleen (the risk for this is greatest when oxygen levels are low, such as in places high above sea level)
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