Platelets are spherical nuclear-free cells with a diameter of 2-4 microns (micrometer). These cells, along with leukocytes and platelets, belong to the formed elements of the blood. They are called blood platelets. In the bloodstream, the bulk are mature platelets - approximately 87%, old cells - 4.5% and young or immature - 3.2%. The ripening period of the blood platelets lasts an average of 8 days. Platelets are in the bloodstream from 9 to 11 days.
The norm in men, women and children will be slightly different. In addition, depending on the age of the person, it also changes. In addition to white blood cells, hemoglobin, erythrocyte sedimentation rate (ESR), and a white blood cell count, a general indicator includes a platelet count. The norm in men of these cells is from 180 to 400 billion per liter.
Where are they formed and destroyed?
Platelets are formed from large megakaryocyte cells that are almost completely filled with cytoplasm. These are giant red bone marrow cells. In a day, approximately 70 thousand new blood platelets, platelets, are formed in the body. Small fragments of the megakaryocyte cytoplasm separate and enter the bloodstream - platelets form. Further, these cells mature, perform their functions, and after 9-11 days are destroyed in the spleen. This body is responsible for the exclusion from the bloodstream of shaped elements with a broken structure that have served their term.
From one megakaryocyte, up to 8 thousand platelets can form. A special hormone, thrombopoietin, which is synthesized in the liver, kidneys, and skeletal muscles, is responsible for the development of these bone marrow cells in the body. From there, with a blood stream, it enters the red bone marrow. And there it regulates the formation of megakaryocytes and platelets. With an increase in platelet blood, the synthesis of the hormone thrombopoietin is inhibited.
Physiological properties
Platelets play an important role in physiological processes. They perform the following functions:
- Primary bleeding stop.
- Maintaining vascular tone and permeability.
- Protective reactions.
- Together with leukocytes, they are involved in the elimination of inflammatory processes.
- Maintaining blood in a liquid state.
But their hemostatic function is most pronounced. When a blood vessel is damaged, its lumen is reflexively narrowed. Platelets interact with collagen (they stick together) and a blood clot forms, which helps stop bleeding.
What affects platelet count?
We will find out what influences such an indicator as platelets. The norm in men is slightly higher than in women and children. Platelet count, among other things, affects both children and adults. So, in newborns, the range of platelet norm is very wide and ranges from 100 to 420 x 10 9 / l (billion / l). This scatter is due to the fact that the circulatory system of newborns is very unstable and platelets, like other formed elements of the blood, actively develop and die in them. This continues up to a year.
The number of platelets in the blood can have seasonal differences, increase after active physical exertion and have daily fluctuations.
Platelet norm in men, women, children
You can get acquainted with the norms of this indicator in men, women and children depending on age in the table below.
| Platelets | The norm is * 10 9 / l (billions per liter) |
| Men | 180-400 |
| Women | 150-380 |
| Newborn babies | 100-420 |
| Children aged 1 to 3 months | 179-399 |
| Children aged 1 to 6 years | 159-389 |
| Children from 7 to 12 years old | 159-379 |
Some sources indicate that the platelet norm in men is up to 320 x 10 9 / L. This is a bit outdated data.
Platelets: the norm in men
Representatives of the stronger sex can be reduced after 60 years. Depending on the age, some indicators of the general blood test may vary. This also applies to an indicator such as platelets. The norm for men by age of this indicator is shown in the table.
| Age of men | Norm |
| from 18 to 25 years old | 179-380 |
| from 26 to 35 years old | 180-400 |
| from 36 to 60 years | 179-340 |
| after 60 years | up to 320 |
In adulthood, the number of blood platelets may become slightly lower. This table clearly shows how the norm of such an indicator as platelets varies with age. The norm in men of 60 years is slightly reduced in comparison with the values of young people.
What does an elevated platelet count indicate?
In a general blood test, along with hemoglobin, leukocytes, ESR and leukocyte counting , platelets are also an important indicator. The norm for men in their blood is up to 400, for women - up to 380 x 10 9 / l. If this figure is much higher, then this condition is called thrombocytosis. This can cause increased blood clotting. But symptomatically this does not manifest itself. It is often detected absolutely by accident - when a general blood test is taken during a routine examination. Thrombocytosis can occur in the following conditions:
- Oncological processes.
- Myelofibosis
- Chronic inflammatory processes.
- Infectious diseases.
- The postoperative period.
- Erythromia (chronic leukemia).
- After removal of the spleen (splenectomy).
- With iron deficiency anemia.
- As a result of prolonged use of certain drugs, for example, corticosteroids.
All these conditions can cause an increase in such an indicator as platelets. The norm in men in their blood is usually somewhat higher than in women and children. A slight increase in platelets is possible after increased physical activity. This is not a pathology. After rest, this indicator returns to normal. Thrombocytosis is primary and secondary.
Primary thrombocytosis: causes
Primary thrombocytosis occurs as a result of a violation of hematopoiesis (the formation and maturation of blood cells) of bone marrow stem cells. The reasons may be:
- Some forms of anemia.
- Erythromia
- Chronic myeloid leukemia.
- Fibrous degeneration of bone marrow (myelofibrosis).
- Idiopathic thrombocythemia, while platelet count can rise to 4000.
Secondary thrombocytosis: causes
Secondary thrombocytosis develops as a result of pathological conditions (diseases) that disrupt the functioning of the hematopoietic organs. The most common cause of secondary thrombocytosis is infection.
Possible causes of secondary thrombocytosis:
- Rheumatoid arthritis.
- Rheumatism (the correct name for this pathology is acute rheumatic fever).
- Osteomyelitis or purulent-necrotic process in the bone marrow.
- Ulcerative colitis.
- Severe liver disease, such as cirrhosis.
- Tuberculosis.
- Tumor processes, for example, carcinoma, lymphoma or lymphogranulomatosis.
- Great blood loss.
- Acute hemolysis (a serious condition in which red blood cells break down).
What does low platelet count mean?
Thrombocytopenia is a condition in which platelets are reduced in the blood. The norm for men in some sources indicates up to 320 billion cells per liter, in others - 400, and the lower limit in any case is from 180 cells. A decrease in this indicator several times will be considered thrombocytopenia.
The reasons for this may be:
- Infectious processes.
- Functional bone marrow abnormalities.
- Pregnancy and menstruation in women.
- Anemia of various kinds.
- Leukemia.
- Heredity.
- Harmful effects of heavy metals.
- Alcohol in large quantities.
- Massive bleeding.
- Taking certain medications (such as antibiotics, analgesics, estrogens).
Deviations from the normal values of platelets in one direction or another require a thorough examination and treatment, not only with medicines, but also with an appropriate diet.