A low platelet PLT is when the number of platelets in the peripheral blood is below the normal range. A low platelet count can affect the body to varying degrees. If the platelet count is mildly low, it often has no noticeable effect on the body. If the platelet count is severely reduced, the patient will experience significant bleeding. Platelets are the blood cells responsible for stopping bleeding, and when platelet count decreases, the body’s hemostatic function decreases significantly, and the patient may experience a series of bleeding symptoms, such as petechiae on the skin, bleeding from the nose and gums, or internal bleeding such as vomiting blood, black stool, or urine blood. Clinically thrombocytopenia can be seen in a variety of diseases, including aplastic anemia, myelodysplastic syndrome, and severe paroxysmal sleep hemoglobinuria, immune thrombocytopenic purpura, etc., all of which can have severely low platelets.