Thrombocytosis And Anemia: What Is The Link?

Thrombocytosis and anemia are two distinct medical conditions that affect the number and function of certain types of blood cells. 

Thrombocytosis is a disorder characterized by an increase in the number of platelets in the body. These platelets are responsible for blood clotting. When the number of platelets increases, it can increase the risk of heart attacks and stroke.

Anemia, on the other hand, is a condition where the body lacks enough healthy red blood cells. These cells carry oxygen to the body's tissues. When there aren't enough healthy red blood cells, the body's tissues don't get enough oxygen.

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Understanding anemia

Anemia is a condition that affects a person's red blood cells and can cause various symptoms. It is characterized by decreased healthy red blood cell counts and/or lower hemoglobin levels. 

Hemoglobin is an iron-rich protein in red blood cells that carries oxygen to the body's tissues. Anemia, in turn, affects the amount of oxygen that red blood cells can carry. This means less oxygen is distributed through the blood to the body's organs and tissues.

According to the World Health Organization (WHO), anemia affects about 42% of children below five years and 40% of pregnant women worldwide.¹

There are various types of anemia. However, iron deficiency anemia (IDA) is the most common and highly linked to thrombocytosis.

Symptoms of iron deficiency anemia

If you have iron deficiency anemia, you may experience symptoms like:

  • Fatigue and weakness

  • Shortness of breath

  • Pale skin

  • Heart palpitations

  • Fast or irregular heartbeat

  • Headaches

  • Cold hands and feet

  • Restless legs

  • Sore tongue or mouth

  • Brittle nails

  • Spoon nails

  • Poor appetite

Causes of iron deficiency anemia

There are many different causes of iron deficiency anemia, including:

  • Blood loss: Red blood cells contain iron. This means that whenever you lose a lot of blood, like during heavy menstrual periods, bleeding ulcers, or an injury, you also lose iron from your body.

  • Insufficient iron intake: An iron-rich diet like red meat, nuts, eggs, and green leafy vegetables reduces the risk of this type of anemia.

  • Pregnancy: During pregnancy, the body needs more iron to make the larger volume of blood needed to support the fetus's growth. When there is insufficient iron stored in the mother’s body or her iron intake is insufficient, IDA often occurs.

  • Chronic diseases: Several diseases can cause chronic inflammation in the body. These include autoimmune disorders, cancer, chronic kidney disease, liver disease, and HIV/AIDS. When inflammation is present, it can affect the body's ability to absorb nutrients from food or utilize them properly.

  • Malabsorption: Conditions like celiac disease, Crohn's disease, and pancreatitis can lead to decreased absorption of nutrients, including iron, from the intestinal tract.

  • Gastric bypass surgery: Iron from food is absorbed from the small intestine, particularly the duodenum. After this surgery, however, the food is intended to bypass the duodenum, which decreases the amount of iron absorbed from food, leading to anemia and other deficiencies.

How is iron deficiency anemia treated?

Treatment for this type of anemia involves increasing the body's iron. One option is taking oral iron supplements, but you can also improve your diet to include more iron-rich foods. In more severe cases, intravenous iron infusions may be necessary. 

It's important to note that if there's an underlying condition causing iron deficiency, treating that condition can ultimately improve iron levels and help with anemia.

Thrombocytosis explained

Thrombocytosis is a medical condition characterized by an abnormally high number of platelets in the blood. Platelets, or thrombocytes, are important for clotting and help to prevent excessive bleeding.

There are two main types of thrombocytosis: primary and secondary.

Also known as essential thrombocythemia (ET), primary thrombocytosis is a rare blood disorder in which the bone marrow produces too many platelets. It's considered a type of myeloproliferative neoplasm, a group of blood disorders characterized by the uncontrolled growth of blood cells in the bone marrow.²

Secondary or reactive thrombocytosis, on the other hand, occurs when an underlying condition causes an increase in platelet count.

Symptoms of thrombocytosis

Most people will not experience any symptoms due to the disease itself (increased platelet count). Symptoms often only develop when the condition progresses to cause clotting or abnormal bleeding in the body. These include:

  • Fatigue

  • Nosebleeds

  • Easily bruised

  • Blood in urine or stool

  • Blood in gum or mouth

  • Headaches

  • Confusion or slurred speech

  • Chest pain

  • Shortness of breath

  • Seizures

Erythromelalgia is a condition that may occur as a result of primary thrombocytosis. This condition can cause pain, numbness, and tingling in the hands and feet. It may also cause them to become red and swollen. 

What causes thrombocytosis?

Primary thrombocytosis and secondary thrombocytosis have different and unique causes.

Causes of essential thrombocythemia

ET is developed over time when an individual acquires a somatic genetic change in specific genes linked to the condition.

These genetic changes are acquired later in life and not inherited. It’s also worth noting that it’s still unclear why people with ET undergo this genetic mutation. 

Causes of reactive thrombocytosis

There are many different causes of reactive thrombocytosis, including:

  • Cancer

  • Chronic inflammatory conditions

  • Iron deficiency anemia 

  • Infections

  • Trauma or surgical removal of the spleen

  • Certain medications

  • After surgery

  • Some blood disorders

Many other factors could contribute to the development of secondary thrombocytosis.

Treatment for thrombocytosis

Treatment for thrombocytosis involves addressing the underlying cause of the condition. In cases where the cause is a condition, such as cancer or a blood disorder, treatment may involve chemotherapy, radiation therapy, or other forms of treatment. If the cause is a medication, the medication may be discontinued or changed.

In the case of reactive thrombocytosis as a result of iron deficiency anemia, treatment with iron supplements can correct the iron levels and platelet count, resolving the condition.

In cases where the cause is unknown, or the platelet count is very high, medications such as hydroxyurea or anagrelide may be given to decrease the platelet count. In severe cases, plateletpheresis, a procedure where the platelets are removed from the blood, may be performed.³

Who is at risk of developing anemia and thrombocytosis?

Anemia and thrombocytosis can occur in anyone, but certain groups may be at a higher risk.

Women with heavy menstrual periods, pregnant women, and individuals with chronic diseases or malabsorption disorders may be at a higher risk for anemia.

People with autoimmune disorders, cancer, blood disorders, or chronic inflammatory conditions may be at a higher risk for thrombocytosis.

Complications of anemia and thrombocytosis

The complications of anemia and thrombocytosis can vary depending on the cause and severity of the conditions.

Complications of thrombocytosis

If left untreated, thrombocytosis can go on to cause potentially serious complications. These can include:

  • Increased risk of cancer: Primary thrombocytosis can rarely progress to cause leukemia.

  • Increased risk of blood clots: Blood clots can block blood vessels, leading to serious complications such as stroke, heart attack, or deep vein thrombosis.

  • Increased risk of abnormal bleeding, especially in the stomach or intestine

Complications of anemia

If left untreated, anemia can go on to cause potentially serious complications, including:

  • Heart and lung problems: Anemia can cause the heart and lungs to work harder to pump oxygen-rich blood to the body's organs and tissues. This may lead to fast or irregular heartbeat and even heart failure.

  • Reduced immunity: Anemia can also cause the immune system to become weakened. This can make it more difficult for the body to fight off infections.

  • Fatigue: Iron deficiency may lead to reduced oxygen being delivered to body tissues, causing feelings of tiredness and weakness.

  • Pregnancy complications: Anemia can increase the risk of premature birth or low birth weight of the baby, or they may also be born with IDA. Anemia can also contribute to an increased risk of postpartum depression in mothers. 

Are thrombocytosis and anemia connected?

Yes, they are! Many studies have reported a significant association between thrombocytosis and iron deficiency anemia. Platelet count is also found to be often higher in those with lower levels of iron stores or hemoglobin.⁴

Iron deficiency increases the tendency of the body to have a higher platelet count and form clots. Studies have shown that adults who have had an ischemic stroke or venous thromboembolism are 1.4 times more likely to have previously been diagnosed with iron deficiency anemia. And the risk is even greater for children who have suffered a stroke, as they are 3.8 to 10 times more likely to have IDA.⁵

Can iron deficiency anemia cause thrombocytosis?

Yes, IDA can lead to increased platelet production, which can cause thrombocytosis. 

The exact pathway of how IDA can lead to thrombocytosis is not fully mapped, but research studies suggest the following:⁶

  • The mother cells of platelets are called megakaryocytes, and the mother cells of red blood cells are called erythroid. Both megakaryocytes and erythrocytes are sensitive to the amount of iron in the body and share the same precursor progenitor cells (founder of the family). When someone develops iron deficiency, these progenitor cells prefer to produce megakaryocytes (platelets) rather than erythroid (red blood cells). Hence, the individual becomes anemic (fewer red blood cells) and develops thrombocytosis (more platelets).

  • One additional theory has also been proposed. The development of thrombocytosis in IDA individuals may result from an evolutionary adaptation to an iron deficiency caused by blood loss from an injury. The increase in platelet count would boost hemostasis, which aids blood coagulation to stop the bleeding and helps the body heal from the injury.

Can thrombocytosis cause anemia?

In secondary thrombocytosis, which represents the majority of the cases of thrombocytosis, the answer is probably, no. The disease itself won't cause anemia. However, those with primary or essential thrombocythemia may rarely develop myelodysplasia. This stem cell disorder can lead to inadequate production of red blood cells causing anemia.

More often, thrombocytosis itself won’t cause anemia, but its treatments can. These include:


This is a process of taking someone's blood, separating the platelets from it, and then returning back only the plasma and red blood cells to the patient. This can lead to iron deficiency as a result of the loss of some red blood cells in the process.


These include hydroxyurea, one of the main drugs used to treat essential thrombocytosis. It works by suppressing the bone marrow production of blood cells, not only platelets but also leukocytes and red blood cells, causing anemia.

The lowdown

Both thrombocytosis and anemia are conditions that can cause serious complications if not properly treated. This is why you must understand the link between them and the risk factors for developing these conditions.

If you experience symptoms of either thrombocytosis or anemia, it's important to speak with a healthcare professional to get a proper diagnosis and treatment plan.

Frequently asked questions

What causes anemia and thrombocytosis?

Anemia is caused by a lack of healthy red blood cells or hemoglobin, while thrombocytosis is caused by an increased platelet count.

Is thrombocytosis life-threatening?

The condition itself, in the short term, is not serious. However, its complications may lead to the formation of blood clots causing heart attack or stroke. It can also cause severe bleeding, which could be fatal.

Secondary thrombocytosis is easily reversed in many cases, while essential thrombocytosis may have a less positive prognosis as it poses a higher risk to the individual’s life.

  1. Anaemia | World Health Organization (WHO)

  2. Essential thrombocytosis (2023)

  3. Hydroxyurea | Indiana Hemophilia & Thrombosis Center

  4. Thrombocytosis in iron deficiency anemia (2018)

  5. Iron deficiency-induced thrombocytosis increases thrombotic tendency in rats (2020)

  6. Platelet reactivity and platelet count in women with iron deficiency treated with intravenous iron (2022)

Other sources:

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