Platelets are the part of the blood which is mainly responsible for blood clotting. They are made in the bone marrow along with red and white blood cells. They are actually just fragments of cells which make up a small part of the blood volume. They have an important health function. If you have platelet antibodies in the blood, then it means that the immune system is mistakenly creating antibodies to attack the platelets in the blood. People with systemic lupus erythematosus or idiopathic thrombocytopenic purpura may have platelet antibodies. If antibodies have destroyed a considerable amount of the platelets, the doctor may diagnose thrombocytopenia. Sometimes, thrombocytopenia is also caused by taking blood-thinning medicines. Platelet antibodies test looks after the platelet antibodies in the blood in order to find out the cause of low platelet count.