At a Glance Why Get Tested? To determine the number of platelets
in a sample of your blood as part of a health exam; to screen
for, diagnose, or monitor conditions that affect the number of
platelets, such as a bleeding disorder, a bone marrow disease,
or other underlying condition When to Get Tested? As part of a
routine complete blood count (CBC); when you have episodes of
unexplained or prolonged bleeding or other symptoms that may be
due to a platelet disorder A blood sample drawn from a vein in
your arm or by a fingerstick (children and adults) or heelstick
(newborns) Test Preparation Needed? The Test Sample What is
being tested? Platelets, also called thrombocytes, are tiny
cytoplasm fragments of very large cells called megakaryocytes.
Platelets, formed from these large cells in the bone marrow and
released into the blood to circulate, are essential for normal
blood clotting. The platelet count is a test that determines the
number of platelets in a person's sample of blood. When there is
an injury to a