What kinds of infections cause an elevated platelet count?

In one study, the most frequent types of bacteria that cause thrombocytosis are methicillin-resistant Staphylococcus aureus (MRSA), Clostridium difficile, Enterococcus species, Pseudomonas species, and Escherichia coli .

What are possible complications of thrombocytosis?

The most dangerous complication for most people with thrombocytosis is blood clots. Pregnant women also may have serious complications that include miscarriage, slowed fetal growth, or placental abruption .

8 Things That Elevate Your Platelet Count

In general, a platelet count more than 450,000 cells per microliter is considered elevated; this is known as thrombocytosis. There are numerous causes of thrombocytosis and fortunately, the majority are benign and transient. Let's review some of the most common causes.

1

Myleoproliferative Disorders

Human Red blood cells — Micro Discovery / Getty Images

Chronic myleoproliferative disorders (disorders where the bone marrow makes too many blood cells) can cause thrombocytosis. These include polycythemia vera, essential thrombocythemia (ET), and primary myelofibrosis. In ET, for example, the bone marrow makes too many megakaryocytes, the cells that make platelets, resulting in thrombocytosis.

With these conditions, the excessive numbers of platelets cause the blood to be thick and flow more slowly which may result in blood clots. Treatment is aimed at reducing the platelet count to reduce this risk.

2

Infection

Sick woman taking her temperature — Sam Edwards / Getty Images

In both children and adults, infections are the most common cause of an elevated platelet count. This elevation can be extreme, with platelet counts greater than 1 million cells per microliter.

The majority of people who experience this are asymptomatic but a small group of patients with other risk factors may develop blood clots. Platelet counts generally return to normal after resolution of the infection, but this may take several weeks. In some patients, thrombocytosis may be a rebound effect after having thrombocytopenia (low platelets) during initial infection.

3

Iron Deficiency Anemia

Anaemia illustration — ANIMATED HEALTHCARE LTD / SCIENCE PHOTO LIBRARY / Getty Images

Although a low hemoglobin and small red blood cells are the typical laboratory values associated with iron deficiency anemia, elevation of the platelet count is not uncommon. At this time, it is unknown what exactly causes this thrombocytosis. In general, it is well tolerated and resolves with appropriate iron supplementation treatment.

4

Not Having a Spleen

Human pancreas, gallbladder, and spleen, illustration — PIXOLOGICSTUDIO/SCIENCE PHOTO LIBRARY / Getty Images

A certain amount of platelets are housed in your spleen at any given time. If the spleen is removed surgically (splenectomy) or stops functioning properly (functional asplenia) as in sickle cell disease, thrombocytosis results. This thrombocytosis is usually mild to moderate and well tolerated.

Immediately after splenectomy, thrombocytosis may be severe and may trigger the formation of a blood clot. This post-splenectomy complication occurs in about 5 percent of patients. In general, the risk is greatest in the month after splenectomy.

5

Inflammatory Conditions

Illustration of an intestine with Crohn's Disease — JUAN GARTNER / Science Photo Library / Getty Images

Conditions with inflammation, like rheumatologic disorders, inflammatory bowel disease, and vasculitides, can have thrombocytosis. The elevated platelet count occurs in response to cytokines (small proteins released from cells that signal other cells to do something). In particular, the cytokines interleukin-6 and thrombopoietin stimulate platelet production.

6

Mixed Cryoglobulinemia

Hepatitis C virus, illustration — KATERYNA KON/SCIENCE PHOTO LIBRARY / Getty Images

Mixed cryoglobulinemia can cause a false elevation in the platelet count. In this condition, cryoglobulins (proteins) in the blood stick together when exposed to cold temperatures (like the hands and feet).

These particles may be falsely counted as platelets by the machine performing the complete blood count. This condition is associated with hepatitis C infection, systemic lupus erythematosus, and rheumatoid arthritis.

7

Hemolytic Anemia

SEM image showing glucose in blood — SuperStock / Getty Images

If hemolytic anemia (anemia secondary to red blood cell fragmentation) results in the formation of very small red blood cells, these red blood cells may be inaccurately counted as platelets by the machine that performs the complete blood count.

This can be diagnosed by reviewing a peripheral blood smear (a microscope slide of blood). A visual count of the platelets will be lower with many small red blood cells seen.

8

Malignancy

Platelets with a few red and white blood cells — Science Picture Co / Getty Images

Thrombocytosis can be a secondary effect of some malignancies (cancer). This is known as paraneoplastic thrombocytosis. This is more common in solid tumors like lung cancer, hepatocellular (liver) carcinoma, ovarian cancer, and colorectal cancer. Elevated platelet count can also be seen in chronic myelogenous leukemia (CML).

Frequently Asked Questions

What kinds of infections cause an elevated platelet count?

In one study, the most frequent types of bacteria that cause thrombocytosis are methicillin-resistant Staphylococcus aureus (MRSA), Clostridium difficile, Enterococcus species, Pseudomonas species, and Escherichia coli.
What are possible complications of thrombocytosis?

The most dangerous complication for most people with thrombocytosis is blood clots. Pregnant women also may have serious complications that include miscarriage, slowed fetal growth, or placental abruption.