Thrombocytopenia

Platelets (thrombocytes) are small cell fragments produced by megakaryocytes in the bone marrow. Normal platelet count is 150,000-400,000/μL. Platelets are essential for PRIMARY hemostasis — when a blood vessel is injured, platelets adhere to exposed collagen (via von Willebrand factor), become activated, aggregate together, and form a platelet plug that stops bleeding. Thrombocytopenia (platelet count <150,000/μL) impairs this primary hemostasis function, leading to mucocutaneous bleeding — bleeding from skin and mucosal surfaces rather than deep tissues or joints (which characterizes clotting factor deficiencies). The severity of bleeding risk correlates with platelet count: mild (100-150K — usually asymptomatic), moderate (50-100K — prolonged bleeding after trauma or surgery), severe (20-50K — spontaneous petechiae and easy bruising), critical (<20K — risk of spontaneous life-threatening hemorrhage including intracranial bleeding). The practical nurse must recognize the characteristic signs of platelet-related bleeding: petechiae (pinpoint, flat, non-blanching red spots — the EARLIEST sign), purpura (larger purple patches), ecchymosis (bruises), epistaxis, gingival bleeding, menorrhagia, hematuria, and melena. These are distinct from clotting factor bleeding (deep tissue hematomas, hemarthrosis). Thrombocytopenia can result from decreased production (bone marrow problems), increased...