Essential thrombocythemia (ET) is a type of long-term blood cancer where the bone marrow makes too many platelets.^3,9 The platelets are minute blood cells that help in clotting by stacking together to form a clot. In ET, the platelet level can go as high as 450,000 per microlitre of blood.⁶ Having too many platelets may be useful, but anything above the normal limit is always a complication. In ET, platelets become sticky, so they can cause both excessive clotting and unexpected bleeding.⁴ This condition can be accidentally discovered as part of routine blood tests for many patients. While some may notice symptoms like headache, nosebleeding, or burning pain in the hands and feet.¹

This blood cancer is a part of myeloproliferative neoplasms. The conditions that come under this category of cancer have features where bone marrow makes abnormally high blood cells. This can be increased levels in either red cells, white cells, or platelets.² In ET, the platelets are mainly affected, whereas in polycythaemia vera it is red cells, and in primary myelofibrosis it is scar tissue formation.

This type of cancer is very rare. It affects about 30 people in every 100,000 each year.¹ Its occurrence is more common in women than in men. The average age at which this condition can be diagnosed may be around 60 to 70 years, but younger people can also be affected.¹ The common symptoms and clinical presentations of ET must be diagnosed early. It is important because if this condition is untreated, it can lead to life-threatening conditions. They may lead to stroke, heart attack, or major bleeding issues.¹

General clinical spectrum

One of the unusual features of ET is that many people do not have any symptoms at all. You will be wondering how this can be diagnosed. This condition is mostly diagnosed during a routine checkup or during blood tests carried out for another reason.⁴ Although their platelet counts are raised, they may feel perfectly well. They don't show any symptoms of abnormal platelet count.

Some may have the first signs of ET as tiredness or headaches. These symptoms may appear slowly and may be vague.⁴ The symptoms can worsen over time, which includes obvious problems like bleeding or clotting.⁴ This wide spectrum ranges from completely silent to very symptomatic conditions. It means that ET can sometimes be missed unless blood counts are checked.

Common symptoms and presentations

Vascular-related (microvascular) symptoms

The earliest and most frequent symptoms in ET are directed to smaller blood vessels. These microvascular symptoms can be due to the platelets clumping temporarily, blocking the blood flow in the brain, eyes, or fingers.¹

Many patients experience headaches. The pain can be felt like minor pressure, moderate throbbing pain or even as a severe migraine.⁵ Some describe them as being worse in the morning or after physical activity.

Vision problems are also common. They may see lights flashing, zig-zag lines, or regions of blurred vision. Sometimes people may have temporary vision loss, known as “amaurosis fugax”.²

There are a few other symptoms like dizziness, ringing in the years, or inability to concentrate.¹ In severe cases, patients may experience short episodes of weakness, numbness, or speech difficulties. This is medically termed as transient ischaemic attacks (TIAs). This can be due to a temporary interruption of blood flow to the brain due to the clots formed.³

Bleeding tendencies

Although the platelet count is high, bleeding problems occur because the platelets don't work properly. This is medically termed as platelet dysfunction^.4 The most visible signs are easy bruising and nosebleeds.¹ People may notice they develop bruises without remembering any injury.

Gum bleeding is another early clue. Some patients report that their gums bleed a lot when they brush their teeth.¹

This condition can affect women during their menstrual cycle. They may experience Heavier menstruation or a longer cycle. This can affect daily routine and lead to tiredness due to heavy blood loss during menstruation.³

When this condition becomes severe, bleeding can occur inside the body. This cannot be diagnosed as they don't show any symptoms. This includes gastrointestinal bleeding, which may be noted as bloody stools or bloody vomiting. If the internal bleeding occurs in the urinary tract, the blood may appear in urine.³

Thrombotic events

The clot formation or thrombosis is one of the dangerous complications of ET. They are formed due to the aggregation of platelets, which increases the viscosity or stickiness of blood.²

Formation of clots in the arteries that supply the brain can cause stroke. If the clot is formed in the cardiac vessels, it can cause a heart attack. These are life-threatening events if they are not treated quickly.¹

The clots that can be formed in the legs often cause deep vein thrombosis (DVT)¹. The symptoms of DV include redness, swelling, and pain in the affected leg. The clot that breaks or dislodges can travel to the lungs and cause pulmonary embolism, which is the clot that blocks the blood supply to the lungs. This can lead to sudden chest pain, breathlessness, or even collapse.

The clots are not only formed in the major organs but can also be formed in unusual sites such as the veins of the liver, spleen, or intestines. This is called splanchnic vein thrombosis. The symptoms include stomach pain, swelling, or indigestion problems.¹

Microvascular disturbances

Another key factor of ET is erythromelalgia^.1 This includes symptoms like burning pain and redness of the hands and feet. They can also feel warmth in the palms and legs.⁴ Patients often explain these symptoms as they feel their feet are on fire after walking. The symptoms are relieved by the cold pack, but the discomfort often returns. Patients can also feel a tingling sensation or numbness in fingers and toes due to reduced blood flow.⁷ During winter, the fingers and toes may look blue because of poor circulation.¹

Splenomegaly and related symptoms

We all know that the spleen helps store and purify blood. It is a major organ of the lymphatic system. In ET, the blood filtration work is overloaded. So the spleen becomes enlarged, and sometimes it produces abnormal blood cells.³

The spleen enlargement, called splenomegaly, often presents as a sense of fullness or a dull ache under the ribs. This makes the affected people feel full quickly after a meal because of the stomach compression by the organ.¹

Doctors can feel the enlarged spleen during the physical examination by palpation. In severe conditions, the splenomegaly can lead to the inability to do regular day-to-day activities. It can be intolerable for the patients.

Constitutional symptoms (less common)

A smaller group of patients with ET develop more general or “constitutional” symptoms. These include fatigue, which may be due to the disease itself or from chronic bleeding leading to anaemia.⁴

Some patients report night sweats, low-grade fevers, or weight loss. These symptoms may suggest a more advanced form of ET or, rarely, transformation into myelofibrosis or leukaemia.²

Symptom variability

ET does not behave the same way in everyone. Some people live for years without symptoms, while others face serious complications early.³

Age plays a role: younger patients are more likely to be diagnosed incidentally, while older patients have a higher risk of clotting or bleeding.³

Gender also influences presentation. Women are slightly more likely to develop ET, but men may have a higher risk of clotting events.¹

Other factors, such as high blood pressure, smoking, or diabetes, can increase the risk of clotting in ET, making symptoms more likely to appear.

Clinical importance of recognising presentations

It is essential to diagnose the symptoms early to prevent life-threatening complications like stroke or heart attack.⁴

Because many other conditions can cause a raised platelet count, such as infection, inflammation, or iron deficiency. Doctors must distinguish between reactive thrombocytosis and ET.²

Diagnosis usually involves repeated blood counts, a bone marrow biopsy, and tests for genetic mutations such as JAK2, CALR, or MPL.¹⁰

Understanding how ET presents helps guide treatment. Some patients only need regular monitoring, while others may require low-dose aspirin to reduce clot risk or stronger medicines to lower platelet counts.²

Summary

Essential thrombocythemia remains silent for years. It may cause a wide range of symptoms, from mild headaches and nosebleeds to life-threatening clots or bleeding¹.

The most common presentations involve problems with small blood vessels, clotting, bleeding, or spleen enlargement. Less often, patients experience general symptoms like fatigue or weight loss.³Because ET can vary greatly between individuals, awareness of its symptoms is essential for early recognition and timely care. With monitoring and appropriate treatment, many people with ET live long, fulfilling lives.³