What is hemolysis?

Hemolysis is the early breakdown of red blood cells. Sickled red blood cells break down too fast, before new red blood cells can be made. When red blood cells break down faster than the body can replace them, it can lead to hemolytic anemia (low hemoglobin). When you have hemolytic anemia, your organs and tissues don’t get enough oxygen.

Due to this constant stress, red blood cells become damaged. This can cause them to break down earlier than normal (hemolysis).

Toggle to see how sickle cell disease affects the blood vessel.

Image of blood vessels in sickle cell disease that shows that hemolysis, early red blood cell breakdown, leads to hemolytic anemia and blockages (vaso-occlusions)Image of blood vessels in sickle cell disease that shows that hemolysis, early red blood cell breakdown, leads to hemolytic anemia and blockages (vaso-occlusions)

Hemolysis causes red blood cells to break down early in the bloodstream, which can lead to hemolytic anemia and contributes to blockages in the blood vessels, called vaso-occlusions.

Red blood cell breakdown (hemolysis) contributes to
blockages (vaso-occlusion)

Sickling leads to blockages and early red blood cell breakdown

Flow diagram connecting red blood cell sickling, hemolysis, and vaso-occlusionFlow diagram connecting red blood cell sickling, hemolysis, and vaso-occlusion

Vaso-occlusions happen when sticky, sickled red blood cells clump together in the blood. This creates a “traffic jam” that keeps oxygen from being delivered throughout the body

  • Vaso-occlusions can cause extreme pain (pain crises or vaso-occlusive crises). These intense pain crises are what most people think of when they think of sickle cell disease
  • When red blood cells break down, blockages are more likely. These blockages can cause even more red blood cell breakdown
  • Blockages result in less oxygen being transported throughout the body, which can lead to organ damage

Blockages (vaso-occlusions) can cause extreme pain crises. Like hemolysis, blockages can lead to organ damage.

Organ damage can happen even in the absence of
frequent vaso-occlusive crises (VOCs)

Frequency of health complications and organ damage in sickle cell disease

People with sickle cell disease withPeople with SCD with
0-1 VOC per year
(n=45)
Retina damage (retinopathy)60%
Gallstones (cholelithiasis)60%
Inflammation and blockages in the lungs (acute chest syndrome)50%
High blood pressure in the lungs (pulmonary hypertension)47%
Kidney(s) leaking blood protein (microalbuminuria)36%
Death of bone tissue (osteonecrosis)24%
Kidney failure (renal failure)21%
Leg ulcer11%
Stroke11%
Prolonged, painful erection (priapism)9%

Based on a 2006 study of 104 adults with main gene types of sickle cell disease in the Netherlands. Adults were screened for sickle cell disease-related complications twice a year in the 7-year follow-up study.