Thrombocytopenia

Introduction

The so-called thrombocytes (blood platelets) are a type of cell in the blood that is responsible for clotting. They are therefore an important component of hemostasis, as they attach themselves to the damaged tissue in the event of injury and thus ensure that the wound closes. If one speaks now of thrombocytopenia, this means that there are too few thrombocytes in the blood. The opposite of this, i.e. too many thrombocytes, would be called thrombocytosis.

When does thrombocytopenia become dangerous?

According to the current DGHO guidelines, a bleeding tendency is classified according to the extent of thrombocytopenia. Physiologically, thrombocyte values are in the reference range of 150. 000 to 350.

000/μl. Prolonged bleeding times occur only with values below 100,000/μl, and no increased bleeding tendency is to be expected with values above this. Between 50,000 and 100,000 μl bleeding usually occurs only in the case of larger injuries.

With platelet counts between 30,000 and 50,000 and a generally longer bleeding time, harmless petechial haemorrhages can be observed. Serious consequences are therefore only to be expected with values below 30,000 per μl. These can be spontaneous bleeding into the brain (intracerebral bleeding) or the organ system. Disseminated petechiae on the skin and mucous membranes also occur.

Causes

There are several causes for a lack of platelets. However, they can be roughly divided into two areas: either too few functional platelets are produced or the consumption or breakdown in the blood is too high. Like most blood components, platelets are produced in the bone marrow.

If the bone marrow is damaged, this can result in reduced platelet production. The causes of bone marrow damage are manifold, but it is mostly caused by toxins, such as drugs, radiation, intoxication with lead, etc. or through cancer, especially leukemia.

There are also rare basic genetic diseases (e.g. Wiskott-Aldrich syndrome) that limit the function of the bone marrow. A lack of vitamin B12 or folic acid can also lead to reduced production, as these are important components of the blood platelets. If the production in the bone marrow is not restricted, the life span of the platelets in the bloodstream is probably shortened.

A pathologically increased breakdown of the blood platelets can be responsible for the deficiency. The cause could be an autoimmune defect, in which our body’s own defense system increasingly breaks down the thrombocytes. Disease examples for this would be the so-called Lupus erythematodes or the rheumatoid arthritis.

Also medicines or cancer illnesses can increase the dismantling. Finally, platelet consumption can also be increased by damage to artificial heart valves, dialysis or certain infections (e.g. EHEC). Pregnancy can also lead to a reduced platelet count.

HIT syndrome (heparin-induced thrombocytopenia) is a reaction in the form of thrombocytopenia in a small number of people to the medication given to prevent thrombosis or to thin the blood, heparin. There are two types of HIT syndrome. HIT type 1 is a harmless variant and is usually not symptomatic.

HIT type 2 on the other hand can be life-threatening. An immune reaction of the body occurs and as a result antibodies develop. The antibodies activate the blood platelets.

The active blood platelets cause increased blood clotting, which can lead to blood clots (thrombi) in arteries and veins. In addition, disorders can occur in the very small blood vessels and lead to tissue damage due to the disturbed blood flow. The consumption of thrombocytes leads to a decrease in the thrombocyte concentration by more than half.

In everyday language, leukemia is called blood cancer. In leukemia, the formation of new blood cells is disturbed. There are different types of leukemia, which are caused by different factors.

It is possible that thrombocytopenia forms in leukemia. In most cases, the formation of leukemia cells leads to a displacement of normal blood formation in the bone marrow, which also affects the formation of thrombocytes in the bone marrow. In addition to the thrombocytes, the formation of the other blood cells is also impaired.Chemotherapy is often initiated for various types of cancer.

Chemotherapeutics or cytostatics are powerful drugs that are often accompanied by side effects. Many chemotherapeutic drugs can impair blood formation in the bone marrow. Thus, different types of blood cells can be affected in their formation, including the thrombocytes.

In addition to thrombocytopenia, a reduction in white blood cells can also occur (leukocytopenia). Cirrhosis of the liver is the loss of healthy liver tissue. This is triggered by various liver diseases such as inflammation of the liver (hepatitis) or by long-term alcohol abuse.

Cirrhosis of the liver can have numerous consequences, including the so-called esophageal varices or cancers of the liver. Cirrhosis of the liver can also lead to thrombocytopenia. The liver normally cleans our blood.

For this purpose, it receives an inflow through the so-called portal vein circulation. If the liver function is now restricted, this results in a backlog of blood in this venous system. This now also affects the spleen, which becomes larger due to the increased backlog of blood and thus “temporarily stores” a lot of blood.

This also leads to a rearrangement of the thrombocytes. These are no longer distributed evenly in the bloodstream but are stored to a large extent in the spleen. This is why the symptoms of a platelet deficiency also occur here.

There are many drugs that can trigger thrombocytopenia. Heparins in particular can trigger thrombocytopenia in the context of HIT syndrome. Other active ingredients of drugs that can cause thrombocytopenia include: Abciximab, Eptifibatide, Tirofiban, Penicillamine, Linezolid, Sulfonamide, Vancomycin, Carbamazepine or Gold Salts, Valproate, Paracetamol, Rifampicin, Ibuprofen, Cimetidine, Diclofenac, Quinine, Hydrochlorothiazide or Oxaliplatin. There are other drugs that can cause thrombocytopenia. If you want to know exactly what the side effects of a drug are, such as thrombocytopenia, you should read the package insert carefully.