Low Platelet Count: Causes, Symptoms, and Underlying Health Conditions

Thrombocytopenia, commonly known as low platelet count, is diagnosed when a blood test reveals platelet levels below 125×10⁹/L. When platelet counts drop further—typically under 70×10⁹/L—the risk of spontaneous bleeding increases significantly. Common signs include petechiae (small red or purple spots on the skin), bleeding from mucous membranes such as in the mouth, and in women, abnormally heavy menstrual periods. These symptoms serve as important clinical indicators that something may be disrupting normal platelet production or function.

What Causes Thrombocytopenia?

Low platelet count is not a standalone disease but rather a symptom of various underlying medical conditions. The root cause can typically be traced to one of three mechanisms: decreased platelet production, increased platelet destruction, or abnormal distribution within the body. Understanding these mechanisms helps identify the specific disorder responsible for the condition.

Bone Marrow Disorders: Impaired Platelet Production

Aplastic anemia is a serious condition where damage to hematopoietic stem cells and the bone marrow microenvironment leads to reduced production of all blood cells, including platelets. This failure in blood cell generation results in thrombocytopenia, leaving patients vulnerable to uncontrolled bleeding and infections. Exposure to toxins, radiation, certain medications, or autoimmune reactions can trigger this form of marrow failure.

Immune-Mediated Platelet Destruction

Immune thrombocytopenia (ITP) occurs when the body's immune system mistakenly targets and destroys its own platelets. In ITP, there's often impaired maturation of megakaryocytes—the platelet-producing cells in the bone marrow—as well as disrupted platelet release into circulation. Additionally, autoantibodies in the bloodstream accelerate platelet clearance, leading to a sharp decline in platelet count. While ITP can affect people of any age, it's more commonly diagnosed in children following viral infections and in adult women.

Leukemia and Other Blood Cancers

Acute leukemia, a type of aggressive blood cancer, involves the uncontrolled proliferation of abnormal white blood cells. These malignant clones crowd out healthy cells in the bone marrow, severely impairing the production of platelets, red blood cells, and normal white blood cells. As a result, thrombocytopenia becomes a hallmark feature of acute leukemia, often presenting alongside fatigue, frequent infections, and easy bruising.

Early diagnosis and targeted treatment are crucial for managing thrombocytopenia effectively. Depending on the cause, interventions may include corticosteroids, intravenous immunoglobulin therapy, splenectomy, or chemotherapy in cases of malignancy. Patients experiencing persistent bleeding symptoms or unexplained bruising should seek prompt medical evaluation to determine the underlying cause and begin appropriate care.