What is it about ?
Blood cells have a limited lifespan. Our bone marrow must therefore constantly produce new blood cells throughout our life. The number of white blood cells and their different types as well as the number of platelets are determined during a standard blood test. The values obtained are part of what is called “the blood count”.
In the analysis of white blood cells, a distinction is always made between their different types: neutrophils, lymphocytes, eosinophils, monocytes and blasts. Each of these types of white blood cells has a specific function.
- Neutrophils and lymphocytes provide defense against infections.
- Eosinophils are involved in allergies.
- Monocytes have a role in the immune system.
- Blasts are precursors in the permanent production of new blood cells.
Platelets play a role in blood clotting.
The results are expressed as the number of cells per liter of blood. They are always compared to the reference values. Age-specific benchmarks have been established for children. Platelet values in children do not differ much from those seen in adults.
White blood cell deficiency
Children often have a reduced white blood cell count. In most of these cases, the number of neutrophils is less than 1 billion per liter (1.0 x 10 ^ 9 / l). This is called neutropenia. The cause may be disease or reduced production in the bone marrow. The main cause is a viral infection. The neutrophil deficiency goes away once the infection has passed.
However, if the neutrophil count is too low in a newborn baby, it is a warning sign of a possible serious early infection. Persistent neutrophil deficiency in early childhood can be a sign of an autoimmune disease, in which the immune system is not working properly, or it can be due to medications.
In rarer cases, the bone marrow produces fewer white blood cells. This may be due to cancer, such as leukemia, or to a congenital or acquired syndrome that affects the production of white blood cells.
Excess white blood cells
a higher than normal white blood cell count may be due to:
- bacterial infection (many neutrophils);
- the whooping cough or the mononucleosis (many lymphocytes);
- a leukemia (many blasts, few neutrophils);
- a drug (eg cortisone);
- eosinophilia (for example in case of parasitic infection or allergy);
- physical stress, pain or anxiety.
If the amount or distribution of white blood cells is abnormal, it may be helpful to look at the cells under a microscope to check their shape.
Sometimes it is necessary toexamine the bone marrow directly, for example if an underlying cancer is suspected, such as leukemia. Most often, other abnormalities are also present, for example swelling of the spleen or liver, a persistent or very pronounced deficit of neutrophils, an increase in the number of blasts, a tumor or a simultaneous decrease in the number of red blood cells. and platelets.
Lack of platelets (thrombocytopenia)
Slight decreased number of platelets (between 100 and 150 x 10 ^ 9 / l) is common in children; it is often caused by a viral infection such as the common cold or flu. It can also be due to decreased production of platelets in the bone marrow or increased platelet degradation.
Platelets (thrombocytes) are important for blood clotting. There is an increased risk of bleeding if the platelet count drops below 50 x 10 ^ 9 / L due to a production defect or below 30 x 10 ^ 9 / L due to increased degradation . A child with a platelet deficiency and who is bleeding must be hospitalized urgently.
Sometimes the drop in platelet count is actually a pseudo-trombocytopenia. The platelet count is disturbed after the blood test is due to a reaction in the collection tube.
Excess platelets (thrombocytosis)
In children, a increased platelet count is almost always:
- a reaction to another problem, for example:
- bleeding;
- a iron deficiency ;
- an infection ;
- inflammatory disease;
- or the consequence of, in particular:
- a surgical intervention ;
- taking certain medications.
Very rarely, the trombocytosis in children is a sign of a bone marrow disease.
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