What is spherocytosis?

Spherocytosis is a medical condition. If you have it, then your red blood cells are an unusual shape. The general population have red blood cells that are biconcave, their red blood cells look a bit like a ring donut with the hole in the middle filled in. Those with spherocytosis have red blood cells that resemble a ball or sphere.

The spherical shape occurs because a protein that forms part of the structure of a red blood cell is different to normal. A genetic mutation is the usual reason for this, but it can also happen with some autoimmune diseases where the body degrades its own red blood cells.

When spherocytosis is caused by a genetic mutation, it is known as hereditary spherocytosis. This occurs at a incidence of around 1 in 2,000. This level of incidence is typical across races. For more information, see the Incidence of spherocytosis article.

The spherical red blood cells are called spherocytes. They do not survive for as long. A biconcave red blood cell would typically survive for around 120 days, whereas a spherical one might only last 20 days.

The red blood cells are destroyed by a process called hemolysis. When the spherocytes pass through a narrow point in the spleen they are trapped and put under stress. While they are trapped they come under attack from immune cells. The extra stress on the red blood cells causes damage, which can attract the immune cells. For more information, see the Spherocytosis: the spleen and splenectomy article.

The higher rate of hemolysis (red blood cell break down) in those with spherocytosis leads to two changes which potentially cause symptoms: fewer red blood cells and higher levels of red blood cell break down products. The severity of symptoms is directly related to the severity of these changes.

Having fewer red blood cells is called anemia. It lowers the body’s ability to transport oxygen round the body. This can lead to a paler skin colour and fatigue. In more extreme cases, the body does not get an adequate level of oxygen. This is known as hypoxia and it can cause headaches, shortness of breath, lowered consciousness or death.

Bilirubin is the product of hemolysis that causes the most significant problems. A high level of bilirubin in the blood causes jaundice. This means that the skin and the whites of the eyes turn yellow. The whites of the eyes are usually the first place this yellowing can be seen. Jaundice caused by hemolysis does not generally cause any problems other than the yellowing, but for infants it can cause brain damage.

If levels of bilirubin are higher than normal over an extended period of time, as is often the case with spherocytosis, this can lead to a build up of bilirubin in the gall bladder and consequently an increased risk of gall stones. A gallstone that enters any of the ducts leading away from the gallbladder is extremely painful and, if a duct becomes blocked, life threatening conditions can quickly develop. For more information, see the Spherocytosis and gallstones article.

Under some circumstances, hemolysis can be temporarily much higher. This can be caused by an infection, for example. This can dangerously increase the severity of symptoms in a person with spherocytosis. For more information, see the Spherocytosis: hemolytic crisis and aplastic crisis article.

Because those with spherocytosis have higher level of hemolysis, the spleen can become enlarged due to the increased demands on it. Often the spleen becomes large enough for a doctor to feel it during a physical examination of the abdomen.

A diagnosis of spherocytosis can be confirmed using either a blood smear, osmotic fragility test, cryohemolysis, or genetic testing. In a blood smear test, the shape of the red blood cells is determined by direct observation under a microscope. The osmotic fragility test measures the strength of the red blood cells. Cryohemolysis looks at how the blood cells react to cold temperature. A genetic test examines various gene sequences looking for the mutations known to lead to spherocytosis. A child should be tested at birth if either parent is known to have spherocytosis.

Once a diagnosis has been made, there are a number of treatment options. The recommended treatment depends on the severity of symptoms. For those with a relatively mild condition, an increase in the intake of folate acid may be helpful. Folate acid is used by the body to create new red blood cells. Folic acid is a form of folate that can be taken as a tablet.

If you take folic acid supplements then you should also consider taking vitamin B12. A lack of vitamin B12 causes anemia and neurological damage. Taking folic acid masks the anemia that a vitamin B12 deficiency can cause, so it is likely that the vitamin deficiency would only be detected at a much later stage, once irreversible neurological damage had occurred.  For more information on folic acid and B12, see the Treating spherocytosis with vitamins article.

Where the symptoms of spherocytosis are more severe, the spleen can be removed (splenectomy). Typically, this significantly reduces or eliminates all symptoms of spherocytosis. There are relatively rare, but serious complications associated with having no spleen, including sepsis (blood poisoning) and pneumonia, both of which can be fatal. Because of this, pneumococcal vaccines and influenza vaccines should be given regularly to those with no spleen. For more information, see the Spherocytosis: the spleen and splenectomy article.

If a person with spherocytosis is suffering from a pronounced anemia due to a low number of red blood cells then blood transfusions may necessary. However, numerous blood transfusions can raise levels of iron because the body does not easily dispose of the extra metal ions that are introduced with the transfused blood. This can lead to hemochromatosis, a serious condition that can cause liver damage. Those with spherocytosis are also at a higher risk, compared to the general population, of having a genetic form of hemochromatosis.

Trials of experimental gene therapy have successfully altered a spherocytosis gene in mice bone marrow cells, but it is unlikely that this will be available for human treatment in the near future.

Longer term monitoring of red blood count levels is common for those with spherocytosis, especially if you still have your spleen. Blood might well be tested for levels of haemoglobin, a component of red blood cells. The result is normally given in grams per decilitre. A normal adult would have between 12 and 18. Someone with mild spherocytosis might have a test result of around 11. Severe cases might score around 6. A score of 4 or 5 would require immediate blood transfusion.

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