What causes low platelets in blood test

A low platelet count means that your blood is lacking the small cells it needs to form clots. Autoimmune disease, infections, and conditions that affect bone marrow can cause low platelets. In rare instances, it can be related to a genetic disorder.

Having low platelets, known as thrombocytopenia, can be life-threatening. Your body might not be able to stop blood flow if you're injured, and you could be at risk for excessive bleeding.

This article discusses normal and abnormal platelet counts, some of the causes of low platelets, and symptoms you may experience. It also describes strategies for managing the condition and how it is usually treated.

Normal and Abnormal Platelet Counts

A complete blood count (CBC) test is a standard panel of bloodwork. The platelet count is one of things this test measures. Here is what various platelet counts mean:

• Normal: Between 150,000 and 450,000 platelets per microliter of blood
• Low: Below 150,000 platelets per microliter
• Mild bleeding risk: Below 50,000 platelets per microliter
• Serious bleeding risk: 10,000 to 20,000 platelets per microliter or lower.

Genetic Causes of Low Platelets

Thrombocytopenia can be genetic, which means it is passed down through families. Genetic forms are rare. They are sometimes misdiagnosed as other forms of the disease.

Platelet Dysfunction or Destruction

Your body may produce enough platelets on its own, but some conditions and medicines may destroy them or stop them from working correctly (dysfunction).

Autoimmune Conditions

When you have an autoimmune condition, your immune system attacks healthy cells. Diseases like lupus and rheumatoid arthritis may cause the immune system to destroy platelets.

Bacterial Blood Infections

Bacteremia, also called blood poisoning, is a bacterial infection that affects the blood. This infection may lead to a reduction in platelets.

Medication

Anticoagulants are medications that stop your blood from clotting. Heparin Sodium ADD-Vantage (heparin) is an example of this type of medication.

Decreased Platelet Production

Thrombocytopenia can also happen when your body doesn't make enough platelets. There are several reasons this might happen.

Pregnancy

Gestational thrombocytopenia is fairly common in the third trimester of pregnancy. It happens because of an increase in blood volume.

The platelet counts stay the same in this condition, but since the blood volume is higher, the platelets are more diluted. There is usually a low risk of serious bleeding.

Chemotherapy and Radiation

Chemotherapy and radiation are common therapies for cancer. They are very effective at killing cancer cells. Unfortunately, they can't tell the difference between cancer cells and healthy cells.

These therapies target any cells that reproduce quickly. This includes cells in bone marrow. Cancer treatments may unintentionally kill the cells in bone marrow that produce platelets. When this happens, your body won't be able to produce the platelets it needs.

Leukemia

Blood cancer may also cause low platelets. When bone marrow is invaded by cancer cells, healthy cells can be crowded out by cancer cells. This will affect the production of platelets.

Nutritional Deficiencies

Poor nutrition can cause low platelet counts. To make platelets, your body needs nutrients like vitamin B12 and folate.

Viral Infections

Certain viral infections such as hepatitis C or HIV can prevent bone marrow from making platelets.

Heavy Alcohol Use

Heavy drinking can cause malnutrition, which is when your body doesn't get enough nutrients.

People who drink a lot of alcohol may have bone marrow abnormalities. When this happens, your body has trouble making new platelets. Alcohol itself may have a toxic effect on bone marrow.

Recap

Many conditions can cause a decrease in the production of platelets. These conditions often prevent bone marrow from making platelets.

Certain viruses, poor nutrition, and heavy alcohol use can impact your body's ability to make platelets. Blood cancer and cancer treatment can also have this effect.

Enlarged Spleen

Several conditions may result in an enlarged spleen. A healthy spleen stores up to one-third of the body's platelets.

An enlarged spleen may trap platelets. This will prevent them from entering the bloodstream.

Symptoms of Low Platelets

A low platelet count can cause a variety of symptoms. Call your doctor if you notice these issues or if they become more frequent or severe:

• Easy bruising, also called purpura
• Petechiae, tiny red spots on your skin
• Excess bleeding after even minor injuries
• Pain in your joints, particularly large joints like the knees and hips
• Frequent nosebleeds
• Bleeding from the mouth or gums
• Blood in the urine or stool
• Headaches

It is important to call your healthcare provider at once if you have any of the following symptoms:

• Headache, confusion, or dizziness
• Blood when you cough or difficulty breathing
• Blood in your urine, vomit, or stool
• Vaginal bleeding after menopause or unusually heavy vaginal bleeding

Managing Low Platelets

You can limit problems caused by low platelets by doing things that lower your risk of bleeding:

• Avoid certain medications. This includes nonsteroidal anti-inflammatories (NSAIDs) like aspirin and Advil (ibuprofen). If you are taking blood thinners, ask your doctor about the risk of bleeding.
• Use an electric razor to shave. This may result in fewer nicks and cuts.
• Use extra care when working with sharp objects such as knives or scissors.
• Avoid contact sports​.
• Use an extra-soft toothbrush. Inflamed gums bleed more easily when flossing. Diligent mouth care will reduce gum inflammation. Avoid flossing when your platelet count gets very low.
• Blow your nose gently. This will help you avoid a nosebleed.
• Limit or avoid alcohol.

Recap

You can limit the problems caused by low platelets by taking steps to avoid injury. It also helps to avoid certain medications and limit your intake of alcohol.

What to Do If Bleeding Starts

Bleeding can be a serious concern in someone with a low platelet count. If you begin bleeding, contact your doctor at once. Follow these steps to minimize bleeding:

• Sit or lie down. Try to stay calm.
• Apply pressure to the wound if you can see it.
• Apply an ice pack to the site to slow the bleeding.
• If the wound is on an arm or leg, raise the limb above the level of your heart.
• If you see blood in your urine, increase your fluid intake and call your doctor at once.
• If you notice blood in your vomit, call your doctor. Take anti-nausea medications and antacids as instructed by your doctor.
• If you are bleeding vaginally, do not use tampons. Keep track of how many sanitary pads you are using. Note any clots.

Recap

If you have a low platelet count and you begin bleeding, call your doctor right away. Bleeding can be minimized by applying pressure and/or ice and elevating the wound.

Treatment of Low Platelets

It is important to identify the cause of low platelets. When the cause is clear, treatment can usually help your levels return to normal.

If you are receiving therapies that affect your platelet count, such as cancer treatment, your platelets should return to normal once the treatment ends. Keep in mind that the timeline is different for everyone.

In some cases, a platelet transfusionmay be needed. This is a procedure where you receive platelets from a donor through a vein. A transfusion can help prevent complications from bleeding.

Autoimmune conditions can be treated with drugs that suppress your immune system. This will help stop the destruction of platelets.

When low platelets are caused by medication, the solution is often just switching medications. Your doctor will help you find the right alternative drug.

Recap

When the cause is known, low platelets will usually resolve with treatment. You may need to change medication or wait until you are done with treatments like chemotherapy. Platelet transfusions are sometimes required.

Summary

People with thrombocytopenia have a low number of blood platelets. This can lead to problems with excessive bleeding.

Low platelets may be genetic. Typically, though, low platelets are caused by conditions that either lead to the destruction of platelets or prevent platelets from forming. Certain medications or therapies like cancer treatment may also cause low platelets.

People with low platelets have a variety of symptoms including excessive bleeding and easy bruising. Low platelets can be managed by avoiding situations that might cause bleeding.

The condition usually gets better once the cause is understood and the patient gets treatment.

Low platelets, or thrombocytopenia, are a common side effect of blood cancers and their treatment. They can also be caused by autoimmune diseases, pregnancy, heavy alcohol consumption, or certain medications.

When you have low platelets, you may have frequent or excessive bleeding. It is important to try to avoid injury. This will help prevent dangerous complications.

Frequently Asked Questions

• What are the causes of thrombocytopenia?

  The causes of thrombocytopenia include reduced platelet production in the bone marrow, drug-induced thrombocytopenia, leukemia, deficiency in vitamin B12 and folate, cirrhosis (liver disease), enlarged spleen, immune thrombocytopenia (a disorder that causes the immune system to attack platelets), and thrombotic thrombocytopenic purpura (abnormal clotting that leads to lower platelet count).

• What medications cause low platelets?

• Can you take a platelet test at home?

  No, you cannot take either type of platelet test at home. Both tests are low-risk and performed by a healthcare provider. The two types of platelet test include a platelet count test and a platelet function test.

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

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Additional Reading

• Mitta A, Curtis BR, Reese JA, George JN. Drug-induced thrombocytopenia: 2019 Update of clinical and laboratory data. Am J Hematol. 2019;94(3):E76-E78. doi:10.1002/ajh.25379

• Nagalla S, Sarode R. Recent advances in understanding and management of acquired thrombocytopenia. F1000Res. 2018;7:68. doi:10.12688/f1000research.12309.1

By Karen Raymaakers
Karen Raymaakers RN, CON(C) is a certified oncology nurse that has worked with leukemia and lymphoma patients for over a decade.

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