Some info on platelet counts...sorry, no time for citations - from ACS site.
Why Cancer Patients Might Need Blood Product Transfusions
Blood product transfusions are used to replace important components of the blood when there are not enough in the body, either because they are not being made or because they have been lost. There are many possible reasons people might need blood product transfusions, such as major bleeding (due to trauma or surgery) or diseases and treatments that slow production of blood cells.
People with cancer might need blood transfusions because of the cancer itself. For example:
Some cancers (especially digestive system cancers) can cause internal bleeding, which can lead to anemia (too few red blood cells).
Cancers that start in the bone marrow (such as leukemias) or cancers that spread there from other places may crowd out the normal blood-making cells, leading to low blood counts.
People who have had cancer for some time may develop what is known as anemia of chronic disease.
Cancer can also lower blood counts in other ways by affecting organs such as the kidneys and spleen, which are involved in keeping enough cells in the blood.
Cancer treatments may also lead to the need for blood transfusions:
Surgery to treat cancer is often a major operation, and blood loss may create a need for red blood cell or platelet transfusions.
Most chemotherapy drugs affect cells in the bone marrow. This commonly leads to low levels of white blood cells and platelets, which can sometimes put a person at risk for life-threatening infections or bleeding.
When radiation is used to treat a large area of the bones, it can affect the bone marrow and lead to low blood cell counts.
Bone marrow transplant (BMT) or peripheral blood stem cell transplant (PBSCT) patients get large doses of chemotherapy and/or radiation therapy. This destroys the blood-making cells in the bone marrow. These patients commonly have very low blood cell counts after the procedure and may need transfusions.
Red blood cell transfusions
People who have low red blood cell (RBC) counts are said to have anemia or to be anemic. People who have anemia for any of the reasons above may need RBC transfusions because they don't have enough RBCs to carry oxygen to all of the cells in the body. Signs and symptoms of severe anemia can include paleness of the mouth, skin, and nail beds; dizziness; and shortness of breath.
Cancer patients may need transfusions of platelets if their bone marrow is not making enough. This happens when platelet-producing bone marrow cells are damaged by chemotherapy or radiation therapy or when they are crowded out of the bone marrow by cancer cells.
A normal platelet count is about 150,000 to 400,000 platelets per cubic millimeter (mm3). When platelet counts drop below a certain level (often 20,000/mm3), a patient is at risk for dangerous bleeding. Doctors may think about giving a platelet transfusion when the platelet count drops to this level, or even at higher levels if a patient may be at risk of bleeding because of surgery.
If there are no signs of bleeding, a platelet transfusion may not be needed even if the platelet count is low.
Currently there is one drug, known as interleukin-11 (oprelvekin, Neumega®), that doctors can give to help raise platelet counts without transfusion, but it does not work right away and is not widely used at this time.
Cryoprecipitate may be given to replace several blood clotting factors such as:
factor VIII (missing in patients with hemophilia A)
Von Willebrand factor (needed to help platelets work)
fibrinogen (the major part of a clot)
People with hemophilia are now more likely to get pure factor VIII, which can be separated from the rest of the plasma. Unless they are bleeding, people with cancer rarely need cryoprecipitate.
Chemotherapy can damage cells in the bone marrow, and patients getting chemo often have white blood cell (WBC) counts lower than the normal range of 4,000/mm3 to 10,000/mm3.
Granulocytes, especially certain kinds of granulocytes known as neutrophils, are very important in fighting infections. When patients have low WBC counts, doctors carefully watch the number of neutrophils. The blood count that is watched is called the absolute neutrophil count, or ANC. People with neutropenia (an ANC below 1,000/mm3) are at risk for serious infections, even more so if the count stays down for longer than a week.
At one time, granulocyte transfusions were commonly given to cancer patients who could not make enough of these cells on their own or whose granulocytes had been destroyed by disease or medicines. But for many reasons, such transfusions are now rare. First, it is not clear how well the transfusions help in reducing the risk of serious infections. Granulocyte transfusions can also cause a fever known as a febrile transfusion reaction. And they can sometimes transmit infectious diseases, such as cytomegalovirus (CMV), which can be dangerous for people who have weak immune systems.
Instead of transfusing granulocytes, doctors now commonly prescribe medicines called colony-stimulating factors or growth factors to help the body make its own neutrophils. Examples include granulocyte colony-stimulating factor (G-CSF), also known as filgrastim (Neupogen®) or pegfilgrastim (Neulasta®), and granulocyte-macrophage colony-stimulating factor (GM-CSF), also called sargramostim (Leukine®).
Also check out: PLATELETS
PLATELET COUNT TESTS