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Thrombocytes, or platelets (PLT), are small fragments of larger cells that play an important role in blood clotting. The assessment of the number of thrombocytes is an integral part of blood count testing. Find out when to test your thrombocyte counts and what an excess or deficiency shows. What are the norms of thrombocytes?

Thrombocytes or platelets (PLT for short)are disc-shaped fragments of megakaryocytes that mature in the bone marrow. Thrombocytes are the final stage of development of cells in the megakaryogenic system. As the megakaryocyte matures, the amount of genetic material in the cell nucleus and the volume of the cytoplasm increase.

The next stage is the separation of the fragments of the megakaryocyte cytoplasm, from which thrombocytes are directly formed. A single megakaryocyte is capable of producing 4,000-8,000 thrombocytes. Blood is the physiological home of thrombocytes.

Mature thrombocytes do not have a nucleus, but their cytoplasm contains granules containing various bioactive substances such as serotonin, platelet factor 4, and platelet-derived growth factor. Thrombocytes live 7-10 days and then complete their life cycle in the spleen.

Thrombocytes - functions in the body

Thrombocytes are primarily involved in the blood clotting process. When tissue is damaged, the thrombocytes begin to stick to the blood vessels and release a series of chemicals that initiate the blood clotting cascade.

One of them is serotonin, which is responsible for the local constriction of blood vessels. Thrombocytes also activate the conversion of fibrinogen into fibrin molecules, which creates a net that seals the damaged blood vessel.

In addition, red blood cells and thrombocytes are then trapped in this mesh, creating a mechanical plug that prevents the free flow of blood.

Thrombocytes - what is the test?

The thrombocyte count is performed together with the other parameters included in the blood count. The test is performed on venous blood taken from the elbow bend. The test should be performed in the morning, preferably between 6:30 am and 9:00 am.

The person performing the test should be onfasting, i.e. 12-16 hours after the last meal. In the laboratory, the study of the number of thrombocytes is most often performed using automatic hematological analyzers, which analyze the cellular composition of the blood within a few minutes, giving the exact number of thrombocytes and other blood count parameters.

Hence, very often the results of blood counts include additional indicators assessing thrombocytes:

  • MPV - average platelet volume
  • PDW - an indicator assessing the volume of platelets (anisocytosis)
  • P-LCR - percentage of large thrombocytes in the total number of them in the blood

Thrombocytes - norms

The norm of thrombocytes for adults ranges from 150,000 to 400,000 cells per cubic millimeter of blood. On average, the number of thrombocytes in a he althy person is about 250,000 per cubic millimeter of blood. Remember that the norms for the number of thrombocytes may differ slightly between laboratories.

Thrombocytes - when to test?

Abnormal thrombocyte counts can indicate a variety of disease states. A thrombocyte count should especially be requested in the following situations:

  • easy bruising
  • red spots on the skin that look like a rash (ecchymosis)
  • heavy periods
  • chronic nosebleeds
  • intense bleeding from a minor cut
  • the appearance of blood in the stool or blood in the urine
  • suspected intravascular coagulation syndrome (DIC)

Thrombocytes - excess

An increase in the number of thrombocytes above the norm (thrombocytemia, thrombocythemia) is observed:

  • after surgery
  • in proliferative diseases of the hematopoietic system, e.g. polycythemia vera, chronic myeloid leukemia
  • in cancers, e.g. neuroblastoma, pancreatic cancer
  • in graft versus host reaction
  • in collagenoses
  • in diseases of the gastrointestinal tract, e.g. celiac disease, ulcerative colitis, chronic hepatitis
  • in autoimmune diseases, e.g. rheumatoid arthritis
  • in infectious diseases, e.g. tuberculosis
  • after myocardial infarction
  • in nephrotic syndrome
  • in osteoporosis
  • in diabetes
  • during chronic stress

Excess thrombocytes may lead to thrombotic and embolic complications, resulting from increased aggregation of thrombocytes. Therefore, it should be recognized by a doctor as soon as possible. It is worth knowing that an increase in the number of thrombocytes is not always a symptom of pathology and may occur:

  • uinfants between 3-12 months of age
  • in women after childbirth
  • in people staying in high mountain conditions
  • after intense exercise
  • after spleen removal

Thrombocytes - deficiency

A drop in the number of thrombocytes below normal (thrombocytopenia, thrombocytopenia) may be due to:

  • impairment of their production in the bone marrow, e.g. in the course of cancer or bone marrow fibrosis
  • excessive thrombocyte uptake by enlarged spleen
  • excessively rapid removal of thrombocytes from the bloodstream

A decrease in the number of thrombocytes is observed:

  • in hereditary thrombocytopenia caused by genetic mutations
  • in aplasias and marrow fibrosis
  • in proliferative diseases of the hematopoietic system, e.g. aplastic anemia
  • in hematological cancers, e.g. lymphomas
  • in diseases with autoimmunity, e.g. systemic lupus erythematosus
  • in chronic viral infections, e.g. measles, infectious mononucleosis
  • in deficiencies of vitamin B12 and folic acid
  • in renal failure
  • in allergic reactions to certain medications
  • in anaphylactic shock
  • in alcoholism
  • while taking certain medications, e.g. heparin, non-steroidal anti-inflammatory drugs

A dangerous consequence of thrombocytopenia is spontaneous bleeding (hemorrhagic diathesis), which occurs with a thrombocyte count of 10-20 thousand cells per cubic millimeter of blood.

Thrombocytes - pseudo-thrombocytopenia

Occasionally the thrombocyte count from a laboratory test result may be falsely low despite the patient's normal thrombocyte count. In this situation, we are talking about the so-called pseudo-thrombocytopenia, resulting from the presence of natural antibodies in the blood that agglutinate (stick together) thrombocytes in a blood tube taken from a patient.

It is estimated that approximately 2% of the he althy population may possess such antibodies. Alleged thrombocytopenia should be suspected in subjects with significantly reduced thrombocyte counts in the study, but no clinical symptoms of the disease.

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