From the Research
Platelet counts can drop as low as 6 x 10(9)/L in patients with heparin-induced thrombocytopenia (HIT), with a percentage drop in platelet count of 67-96% 1. When platelets are "hit" or activated, they undergo a process called platelet activation, which involves several changes.
- First, platelets change shape from smooth discs to spiky spheres with extended projections.
- They then release chemical signals called granules that contain growth factors, clotting proteins, and other substances that promote clotting.
- These activated platelets become "sticky" and begin to adhere to each other and to the damaged vessel wall, forming a platelet plug. This process is essential for hemostasis, which stops bleeding.
- The power of platelets comes from their ability to rapidly respond to injury, aggregate, and initiate the coagulation cascade.
- This activation process happens within seconds of vessel injury and is crucial for preventing excessive blood loss. Without proper platelet function, even minor injuries could lead to significant bleeding complications. In the context of HIT, the drop in platelet count can be severe, with some studies reporting a median platelet count nadir of approximately 50 to 60 x 10(9) platelets/L 2. It is essential to monitor platelet counts in patients on heparin therapy and to discontinue heparin immediately if HIT is suspected, as the condition can lead to significant morbidity and mortality 3, 4, 5.