Low Platelets And Laboratory Tests

Platelets are also known as thrombocytes. They are found in the bone marrow. They are small fragments or large cells known as megakaryocytes. Platelets are usually released into the blood for circulation and are used in the clotting process.

How Do Platelets Work?

If there is an injury to a blood vessel or a tissue, your body will start bleeding. Platelets will help stop the bleeding in the following ways:

  1. Adhere to the affected area.
  2. Aggregate or clump together with other platelets to create a temporary plug.
  3. Send chemical signals to allow further aggregation of the other platelets.
  4. They also support the coagulation cascade. It’s a process where the clotting factors in the blood are activated to create a blood clot.
  5. Eventually, platelets become a stable blood clot on the injured area. The clot remains in place until the injury is completely healed.

Each microliter of blood contains about 150,000 to 450,000 platelets. A healthy person should have millions of platelets in every single drop of blood. Your body has regular small injuries, so the platelets are repeatedly used up. They can exist for about 8 to 10 days. The bone marrow should produce new platelets to replace the ones that are degraded, lost, or used up through bleeding.

How to Determine the Number of Platelets in Your Body

You can determine the number of platelets in your blood using a platelet count. It is a common test performed as part of a complete blood count (CBC). A CBC can be done as part of your routine health check or when your doctor is examining you for any condition.

The medical professional interprets the platelet count within the context of the other tests performed, such as a CBC, among other factors, including your medical history. If your platelet count is very low, it means your blood has very few platelets.

It means that in the event of an injury, your blood will not clot appropriately, and you are at an increased risk of bruising and excessive bleeding. Keep in mind that a single low platelet count might not necessarily have a huge medical significance. For instance, if the count is slightly lower than the normal range, there is nothing to worry about.

The medical professional should repeat the test and check the previous platelet counts to confirm the same. Any result outside the normal range could indicate a huge problem and prompt further investigation. However, the medical professional should be able to ascertain whether a result outside the normal range is significant in your case.

A low platelet count is also referred to as thrombocytopenia. Various conditions can cause it. It might be acute, where it develops suddenly, temporary or chronic where it persists over time. The risk of serious bleeding because of low platelet count doesn’t happen until you have a very low platelet count (about 20,000 per microliter or even lower).

With a platelet count of about 50,000 per microliter, minor bleeding is present, especially if you have another condition such as kidney disease. The platelet count will drop dramatically depending on the illness, causing the low count.

If you have a severely low platelet count, you are at a high risk of serious bleeding. You should get the necessary treatment to reduce the risk. Several tests will also be performed to determine the exact cause of the low platelet count.

What Are the Causes of a Low Platelet Count?

A few conditions are known to cause a low platelet count. They can be genetic or acquired conditions. If you have an enlarged spleen (happens because of numerous conditions), it will trap platelets, causing a low count.

A low platelet count can be accounted for because of the following:

  • Decreased Production of Platelets

A low platelet count is caused by an interruption of the production of platelets in the bone marrow. Some of the main causes include:

  • Cancer – Some types of cancer such as lymphoma, leukemia, or anything that spreads to the bone marrow will cause a low platelet count. The cancer cells overwhelm the normal bone marrow cells, including the megakaryocytes that form platelets. If you have leukemia, you will have excessive bleeding because of the reduced platelets in the bone marrow.
  • Aplastic Anemia – Here, the bone marrow is failing, so the production of all types of blood cells is reduced significantly.
  • Chemotherapy or Radiation Therapy – If you undergo any of these treatments, the bone marrow’s ability to produce platelets is severely affected.
  • Myelodysplastic Syndrome – It refers to a group of disorders that make the bone marrow ineffective and dysfunctional. As a result, there is reduced production of blood cells, including platelets.
  • Vitamin B12 Or Folate Deficiency – With time, a Vitamin B12 (folate deficiency) can lead to few enlarge red blood cells (a condition known as macrocytic anemia) and fewer platelets.
  • Bone Marrow Infection – Any infections spreading through the blood to the bone or any injury to the bone will result in an infection in the bone marrow. Staphylococcus bacteria mostly cause these infections.
  • Bone Marrow Damage – It is caused by constant exposure to toxic chemicals like benzene or a few types of pesticides.
  • Cirrhosis – It causes reduced production of platelets and a low platelet count.
  • Wiskott-Aldrich Syndrome – It is characterized by a decrease in the size and the total number of platelets in the body. It only affects males.
  • May-Hegglin Anomaly – It results in large misshapen plates reducing the platelets in the body.
  • Gaucher Disease – It is characterized by fatty substances accumulating in the spleen and liver, thus causing them to enlarge and a low platelet count.

Increased Use of Platelets or Destruction

Some conditions lead to platelets being used up and destroyed faster than the bone marrow can produce. It is a huge risk for a low platelet count, but most people with these conditions have a normal count. Some of these conditions include:

  • Viral infections such as hepatitis, mononucleosis, measles, or HIV.
  • Sepsis especially caused by a serious gram-negative bacterial infection such as E. coli or Escherichia.
  • Medication such as quinine, acetaminophen, sulfa antibiotics, vancomycin, digoxin, nitroglycerin, diazepam, gold salts, and diuretics.
  • During pregnancy, platelet count is also known to reduce but remains in the normal range. It is referred to as gestational thrombocytopenia, where the platelet count ranges between 100,000 to 150,000. It happens in at least 10% of women. If the platelet count drops below 100,000, it can be life-threatening and often happens during pre-eclampsia, immune thrombocytopenia, or HELLP syndrome.
  • Dilution – If you receive a massive blood transfusion of red blood cells without getting platelets, you will have a low platelet count.
  • Physical destruction of platelets because of artificial heart valves or medical equipment mostly used during heart bypass surgeries.
  • DIC – It refers to disseminated intravascular coagulation. It is a severe and devastating response that happens because of an infection, burns, or severe trauma. It causes a significant and rapid decrease in the platelets in your body.
  • Hemolytic Uremic Syndrome – It occurs because of a severe toxin that leads to an E. coli infection in the gut, thus destroying red blood cells and platelets.
  • Thrombotic Thrombocytopenic Purpura – It is an acute and life-threatening condition though it’s rare. It leads to clotting and the destruction of red blood cells. Here, tiny clots will form and deposit in various small blood vessels in the body. It leads to the accelerated use of platelets, thus reducing the count. It might be an acquired or genetic condition.
  • Immune-related Conditions – There are some immune-related conditions known to increase the destruction of platelets. The immune system is the natural defense system in the body and protects it against infections. It can distinguish between self and non-self. If you have an autoimmune condition, the body identifies its own proteins as non-self and produces antibodies to target them. The antibodies might target platelets, thus reducing the numbers considerably.

Some of these immune-related conditions include the following:

  • Immune Thrombocytopenia – It is also referred to as immune thrombocytopenic purpura. It affects children. The condition develops after a viral infection and resolves itself after a few months without any treatment. It can affect both boys and girls. In adults, the condition is chronic and affects more women than men.
  • A low platelet count can also be an immune response when you have an autoimmune condition such as rheumatoid arthritis or lupus.
  • Heparin-induced Thrombocytopenia – You will have a low platelet count if you have been on heparin therapy, and your body has a platelet antibody. The condition is characterized by abnormal clotting instead of excessive bleeding.
  • Fetal or Neonatal Alloimmune Thrombocytopenia – It is a rare immune condition and causes a low platelet count in newborn children. It causes when the mother produces antibodies against the developing platelets in the newborn and identifies them as non-self. The antibodies attack and destroy the platelets in the fetus. Most cases of this condition are mild, but serious cases can lead to bleeding and often need treatment.

The Signs And Symptoms To Watch Out For

Depending on your low platelet count, you might not show any signs and symptoms. They are often found during a routine health exam. If the platelet count is considerably low, you might show some of the following signs and symptoms.

  • Unexplained and easy bruising
  • Small red spots on your skin that look like rashes (petechiae)
  • Small purple spots caused by bleeding under your skin (purpura)
  • Excessive bleeding from a wound or a small cut
  • Frequent nosebleeds
  • Bleeding in the digestive tract with black stool
  • Heavy menstrual bleeding
  • Oral bleeding from the gums
  • Intracranial bleeding (inside the head

Tests Needed to Confirm Low Platelet Counts

A low platelet count can be diagnosed, evaluated, and monitored through various blood tests. None of these tests can identify the cause of the low platelet count, but they can be used to identify the right treatment. These include the following:

  • Complete Blood Count It is used to check the current platelet count and to identify if the bleeding has caused anemia (low hemoglobin levels).
  • Platelet Count Checks the number of platelets in the blood, and it is part of the CBC test.
  • Blood Smear It is done using a microscope to check the blood cells, including platelets.
  • Prothrombin Time and Partial Thromboplastin Time It is used to check the clotting factors for proper clotting.
  • Basic Metabolic Panel or Comprehensive Metabolic Panel Checks the overall health of your kidneys, liver, and other organs in your body.
  • Bone Marrow Aspiration and Biopsy – Checks cell production in the bone marrow if you have a low platelet count.
  • Heparin-induced ThrombocytopeniaChecks the antibodies against heparin and diagnoses thrombocytopenia. You can get this test if you have undergone or are currently undergoing heparin therapy.
  • Antiphospholipid AntibodiesUsed to diagnose an existing autoimmune disease such as antiphospholipid syndrome as the cause of the low platelet count or its association with your platelets.
  • Antinuclear Antibody (ANA) Used to diagnose an underlying autoimmune disease such as lupus and its association or cause of low platelets.
  • Vitamin B12 And Folate Any deficiencies in these vitamins cause a low platelet count, anemia, and a low white blood cell count (known as leukopenia).
  • Hepatitis B, C, and HIV – These are viral infections often associated with low platelets. If you have a low platelet count and test positive for these infections, they are the cause of the low platelet count.