Essential Thrombocythemia

Essential thrombocythemia (ET) is a disease of the bone marrow, characterised by a pronounced increase of the number of platelets (thrombocytes) in the blood. This overproduction of blood platelets can increase the risk for blood clots (thrombus formation) and bleeding. In case of a successful treatment, most patients with ET have an almost normal life expectancy.

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Cause

The cause of essential thrombocythemia is still unknown.

Symptoms

Many patients with essential thrombocythemia (ET) remain free of symptoms for a long time.

The symptoms of the disease are determined on the one hand by the sometimes very high number of blood platelets, on the other hand by their functional efficiency. If many platelets with impaired function circulate in the blood stream, bleeding may arise. In contrast, if the function of those platelets is nearly normal, there is a risk for blood clot formation!

Bleeding and Disturbance of the Microcirculation

Bleeding does preferentially occur as nosebleed of gum bleeding, but can also occur in the gastrointestinal tract and on the skin.

If blood clots are formed in the smallest blood vessels, the blood supply of the affected tissue will be impaired. This occurs in about half of the patients and shows itself in the area of fingers and toes as redness with burning, prickling, and swelling (erythromelalgia). Moreover, in the central nervous system it manifests in the form of functional disturbances, such as recurring visual or speech disturbance, dizziness, tendency to fall, paralysis, and even seizures.

Potential Complications

The most common complications of essential thrombocythemia are blot clots (thrombosis) in the venous and arterial system (infarcts). They may occur in the large vessels of the upper abdomen (portal, hepatic, splenic, and mesenteric veins) and the veins of the legs (deep vein thrombosis of the leg), as well as the coronary vessels and the arteries supplying the brain. Since also the general condition of the vessels is important for blood clotting, such events may occur more frequently with increasing age.

Diagnosis

In most cases the suspected diagnosis of essential thrombocythemia is made accidentally in the course of routine blood tests.

Further examinations include:

Analysis of blood picture: Continuing elevation of thrombocyte numbers to >450,000/μl. The function of the blood platelets (thrombocytes) may be impaired in the disease, but may also be normal.
Bone marrow biopsy: This is necessary to confirm the diagnosis of the disease.
Chromosome analysis: The JAK2 V617F gene mutation can be found in chronic myeloproliferative diseases, such as polycythemia vera and essential thrombocythemia. Genetic testing becomes more popular because of its easily accessible and accurate diagnostic parameters. This may reduce the need for additional invasive methods of diagnosis.
Ultrasound examination: Is done to detect enlargement of liver and spleen which can give conclusions about disease progression.