Summary

Thrombocytopenia is a condition that is marked by a low count of platelets, also called thrombocytes. Platelets are a key component of the blood, as they help clot blood in the case of injury thereby preventing loss of blood. A low platelet count can lead to uncontrolled bleeding and various complications some of which can be fatal. Low platelet count can be caused by various conditions. In this article, we will learn all that and more.

Introduction

The blood is made of 4 key components: red-blood-cells which are carriers of oxygen, white-blood-cells which fight pathogens, platelets which help blood to clot, and plasma, a liquid in which the other 3 components are floating freely. The plasma also contains dissolved salts, proteins, water and immunoglobulins.

Platelets, or thrombocytes, are an important component of the blood, as they help blood clot. Whenever there is an injury, platelets in the blood signal to each other to rush to the site of injury. This reaction is called haemostasis. There, they clump together (action called as coagulation) and are bound by sticky fibres made of protein, thereby creating a plug to seal the spot and prevent blood leakage. The wound eventually heals leaving a brown patch of firm material on the surface of the skin, called scab. Once the injury has healed completely, the clot dissolves, and platelets at the spot are freed, to resume circulating in the blood. The scab on the surface of the skin also loosens over time and falls off one day.

In addition to blood clotting, platelets also have other functions such as improving immunity, regulating growth of tumour cells, and associated activities. Needless to say, a healthy count of platelets is important for certain key functions of the body. Thrombocytopenia is a condition where-in the platelet count drops to unhealthy levels, leading to various complications such as uncontrolled bleeding in the case of an injury, and internal bleeding even without an injury.

The normal platelet count in a healthy person is around 1,50,000-4,50,000 per microlitre of blood. A count less than 150000 per microlitre is considered as thrombocytopenia.

It is important to note that platelets are produced in the bone marrow, a sponge-like tissue at the core of the bone. Stem cells present in the bone marrow develop into RBCs, WBCs and platelets.

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Also Read: Testing for Abnormal Blood Flow with Doppler Ultrasound

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Causes and Risk Factors

There are 3 primary reasons for thrombocytopenia:

Not enough platelets are produced by the bone marrow

Reasons for the same include:

• Blood cancers such as leukaemia or lymphoma, which destroys the stem cells in the bone marrow.
• Certain types of anaemia, such as aplastic anaemia, causes the bone marrow to not produce enough of new blood-cells
• Some viral infections such as HIV, hepatitis C and chickenpox
• Chemotherapy drugs and radiation used in cancer treatment can temporarily damage the bone marrow
• Heavy consumption of alcohol can delay production of platelets temporarily. This is especially true if the person has low levels of folate or Vitamin B12
• Exposure to certain toxins such as arsenic or benzene, found in industrial chemicals and pesticides

The body is using up too many platelets

Like all the cells in the body, the platelets too are destroyed after some time, after which new cells are generated by the body. Certain conditions can use up and destroy platelets at a pace faster than the pace at which they are produced, leading to a shortfall in the blood. Causes include:

• Haemolytic uremic syndrome, a condition in which blood-clots form in the tiny blood-vessels of the kidneys leading to a shortage of platelets, and also kidney failure
• Pregnancy can cause mild and temporary thrombocytopenia, especially just before delivery
• Autoimmune diseases like rheumatoid arthritis and lupus, where-in the immune system attacks and destroys the platelets along with certain other cells of the body
• Thrombotic thrombocytopenic purpura (TTP), an uncommon blood-disorder that causes multiple and tiny blood clots all over the body
• Bacterial infections also lead to destruction of platelets
• Medications: Drugs such as anti-seizure drugs, quinine and heparin can confuse the immune system and trigger it to destroy platelets

The spleen is trapping a lot of platelets

The spleen is a fist-shaped organ, around 4 inches long and purple in colour, present on the left side of the abdomen, just below the rib cage. The size and shape can vary slightly. It fights bacteria, and acts as a filter for the blood. That is, it stores platelets and WBCs in order to fight infection. At the same time, it recycles old RBCs.

Certain cancers of the blood, and advanced liver disease can make the spleen enlarged. In turn, the spleen starts holding on to a large number of platelets, resulting in a shortfall of platelets circulating through the body.

Other reasons

• Conditions that cause blood clots: Conditions like thrombotic thrombocytopenic purpura (TTP) and disseminated intravascular coagulation (DIC) cause blood clots to develop even if there is no injury. A lot of platelets in the blood are used up to make these clots, resulting in a shortfall for circulation.
• Surgery: Procedures such as blood-vessel grafts and implants of artificial heart-valves, or equipment used for bypass-surgery or blood-transfusion can destroy platelets.

Symptoms

• Bleeding and swelling in the gums
• Blood in the urine, stools or vomit
• Very heavy menstrual bleeding in women
• Rectal bleeding: traces of blood are found in the stools and toilet-paper after wiping
• Enlarged spleen (sometimes)
• Petechiae: these are tiny blood clots, red or purple in colour, seen on the leg generally
• Purpura: These are large, red, brown or purple spots on the skin. This is caused when tiny blood-vessels underneath the pores of the skin leak blood.
• Bruises: Blood may also pool underneath the skin. This results in bruise or bruise-like appearance even if there has been no injury
• Bleeding in the nose

Complications

Depending on how low is the platelet count, there can be different complications.

• Between 20,000 and 50,000 per microlitre: There can be uncontrolled bleeding after an injury, which can be serious and requires emergency treatment.
• Less than 20,000 per microlitre: There can be slow and internal bleeding even without an injury.
• Below 5,000 per microlitre: There can be severe and spontaneous bleeding even without an injury, and can be fatal.

Diagnosis

• Physical examination: To begin with, the doctor will look for rashes, bruising, petechiae and purpura on the skin.
• Medical History: Then the doctor will ask about symptoms, family history of ailments and medications taken in the recent past.
• Lab-count: Next, the platelet count is determined from a blood-sample of the person
• Other blood-tests: Although the lab-count is enough to confirm low-platelet-count, the doctor will still perform other tests as they are important for determining the treatment. This includes a complete blood count (CBC), blood tests that evaluate the blood-clotting function, and a blood smear test, where-in, the platelets are examined under a microscope.
• Bone marrow tests: This will help determine the source of the problem. There are 2 kinds of tests. Aspiration will use a thin needle to collect a small amount of fluid in the bone marrow. Biopsy will use a slightly thicker needle to collect a sample of the soft tissue in the bone marrow.

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Also Read: Blood Clots, how they form and common causes

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Treatment

• Addressing the underlying problem: The medical condition, or medication, that is causing thrombocytopenia is addressed. Treatment for that ailment will begin immediately, and medication will be changed as required.
• Blood/platelet transfusions: If the platelet level becomes too low, your doctor will augment or supply additional platelets through a full-blood transfusion, or platelet specific transfusion.
• Medications: Conditions that affect the immune system and are causing thrombocytopenia are treated with drugs. Corticosteroids are the first choice, and if that doesn’t work out, stronger medication is used.
• Plasma exchange: In case of thrombotic thrombocytopenic purpura (TTP), low platelet count can trigger an emergency that will require plasma exchange.
• Surgery: If none of the above treatments help, the doctor may perform a surgery to remove the spleen, called as splenectomy.

Kauvery Hospital is globally known for its multidisciplinary services at all its Centers of Excellence, and for its comprehensive, Avant-Grade technology, especially in diagnostics and remedial care in heart diseases, transplantation, vascular and neurosciences medicine. Located in the heart of Trichy (Tennur, Royal Road and Alexandria Road (Cantonment), Chennai, Hosur, Salem, Tirunelveli and Bengaluru, the hospital also renders adult and pediatric trauma care.

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