Aplastic Anemia is a serious condition affecting the blood, where the bone marrow and stem cells do not produce enough blood cells. It is also called bone marrow failure and can happen suddenly (acute) or develop over a period of time (chronic).

Bone marrow is a substance found in the spongy center of bones and is where blood cells are formed. The bone marrow forms ‘stem cells’ which develop into any of the three types of blood cell – red blood cells, white blood cells and platelets. Normally, the bone marrow controls the number of blood cells formed and released into the blood stream, so the body remains healthy. Too many or too few of any of the blood cells can cause problems. The number of blood cells is often referred to as a blood count and is often separated into the different types of blood cells

Red blood cells – about three million red blood cells are produced by the bone marrow every second. They carry a protein called ‘hemoglobin’ which carries oxygen to all parts of the body providing energy. The normal level of hemoglobin in a child’s blood varies with age but is around 10 to 12 grams per deciliter (g/dl). Another name for red blood cells is erythrocytes. White blood cells – these are larger than red blood cells and have different functions. The two main white blood cells are neutrophils – which fight bacterial infections – and lymphocytes – which help fight viruses like chicken pox and measles and other non-bacterial infections. The normal level of all white blood cells in a child’s blood is about six to 16 x 109 /l. The normal level of neutrophils is between 1.5 and 8.5 x 109 /l and lymphocytes between two and 9.5 x 109 /l. Platelets – these are much smaller than red blood cells and help the blood clot by sticking together. The normal level of platelets is between 150 and 400 x 109 /l.

In aplastic anemia, all types of blood cells are reduced. This is called pancytopenia – pan means all, cyto means cells and penia means few. A bone marrow sample, which would normally contain large numbers of immature blood cells, will contain very few such cells in a patient with aplastic anemia. A below normal number of red Ref: 2020F0588 © GOSH NHS Foundation Trust, January 2021 Page 2 of 5 cells is called anemia, reduced numbers of platelets is called thrombocytopenia and a reduced numbers of neutrophils is called neutropenia.

Aplastic anemia can be inherited. It can also develop for unknown reasons – this is called idiopathic aplastic anemia

Aplastic anemia is a rare disease, with about thirty to forty children diagnosed with it each year. It does not seem to affect one race more than another and affects males and females equally. It can affect anyone at any age but seems to occur most often in children and people over 60 years old.