Spherocytosis: hemolytic crisis and aplastic crisis

Often, someone with spherocytosis will have little in the way of symptoms. Perhaps they feel a little more tired than others. This can change dramatically, however, when a hemolytic or aplastic crisis occurs.

A hemolytic crisis is a substantial increase in the rate of destruction of red blood cells (hemolysis). It can be triggered by a variety of parasitical, bacterial or viral infections. For example, both malaria and mononucleosis (also known as glandular fever or mono) can be triggers.

The reason for the increase in hemolysis depends on the type of infection. In a bacterial infection, for example, the immune response increases and this means the spleen has more macrophages (immune system cells that swallow undesirables). This makes the spleen a more hostile environment for spherocytes (the spherical red blood cells that give spherocytosis its name), especially as they spend much longer there than normal red blood cells.

The level of red blood cells falls leading to lethargy, weakness, shortness of breath and the other symptoms of anemia. Levels of bilirubin (a break down product of the red blood cells) increase, leading to jaundice, a yellowing of the whites of the eyes and the skin. In a more extreme hemolytic crisis, there can be vomiting, abdominal pain and a tender, enlarged spleen.

An aplastic crisis occurs when something prevents the creation of new red blood cells. Some infections have this effect, in particular, parvovirus B19, otherwise known as erythrovirus B19 or fifth disease.

Parvovirus B19 can cause a rash, fever and inflammed joints. The virus attacks stem cells in the bone marrow that would mature into blood cells. As a result red blood cell production stops for between 10 and 14 days. In the general population, this causes a small drop in a relatively high red blood cell level. In those with spherocytosis, the drop is larger because the red blood cells don’t last as long and the starting level is also lower. The effect is much more powerful and it can lead to dangerously low levels.

When levels of red blood cells fall too low, whether due to hemolytic or aplastic crisis, then blood transfusions are needed to provide a boost to the red blood cell levels. Folic acid should be taken. More of it will be required as the body replenishes its stock of red blood cells. In rare cases, immunoglobulin might be given to kill off the underlying infection that was the original cause of the anemia.

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