When you have low platelets, it's called thrombocytopenia, big fancy term, which thrombocytes are what platelets are and penia means low. So when those are low, we call it thrombocytopenia. And when you have low platelets, you are at risk for bleeding. Generally speaking, that's not nosebleeds, gumbleeds, those types of scenarios unless the number is really low, typically less than 10,000. But you can get little red spots on your skin, which are called petechiae, which is bleeding underneath the skin. It's most typical on your legs, low down, because that's where gravity is, but it can be anywhere. So those are the kinds of things we watch for when patients are thrombocytopenic or their platelets are low. So platelets are the cells that prevent us from having bleeding problems. So when the platelets detect that somebody is bleeding, the first thing they will do is release factors that will constrict the blood vessels. And then the platelets will clump together and form a clot, a plug to try to plug up the leak in the vessels so that there is no longer bleeding. So that's what the platelets typically do. The MPV, the mean platelet volume, is important when we have low platelet count. We don't know whether we have low platelet count because our bone marrow does not produce enough or because our body destroys the platelets much faster than the body can make. If the latter is the case, if the bone marrow releases a normal amount of platelets, but the body destroys the platelets too fast, then you will have a high MPV. The mean platelet volume will be higher. And again, it's because the platelets that are released by the bone marrow have a bigger size than normal platelets. Again, because they are released too quickly, too early. And that's why you have that. If you have low platelet counts and your bone marrow is not making any platelets, all the platelets you will have will be of a smaller size and the MPV will be low. That is still a controversial type of issue. A normal platelet count is 150,000 or higher. The bleeding problems typically do not occur until the platelet count is at least less than 20,000. And 20,000 was a number of platelets that was considered to be at high risk of bleeding if you go below that in the 60s and early 70s when people were still getting aspirin for fevers. And as you know, aspirin affects the platelet function. So the 20,000 is probably still way too high. I am more inclined to give platelets when the platelet count is less than 10,000, not 20,000, so that I can minimize the amount of platelet transfusions to be given. But not only the absolute platelet count is important, but also the degree, the rapidity with which the platelets are dropping. If somebody has a platelet count of 45,000 and the next day it's 20,000, then you know the next day it's going to be under 10,000. And I should give platelets when they are 20,000 and not wait any longer. So there are two important factors, the absolute number and the rapidity with which the platelet count drops. But we have done quite a bit of patients, have given transplants to patients who were Jehovah Witnesses and did not want any platelet transfusions. We were surprised how few bleeding problems we saw in those patients when we took preventative measures to minimize bleeding. So the 10,000 I consider a very safe number. If it's lower than that, you should get a platelet transfusion. Most people still do 20,000. I'm not in favor of 20,000, I'm in favor of 10,000. But then again, if you have somebody who has a transplant as an outpatient, I will typically be a little more conservative than if they are inpatient. Inpatient, I would certainly not give any platelets when they are more than 10,000, unless the platelet count is dropping very rapidly. If they are outpatients, and I see somebody has 15,000 platelets, I will probably already give platelets.