More ways to understand low platelets

How long will it take platelet counts to rise again?

That's the big question, and the answer is: probably within three to four weeks. Doctors can't make an accurate prediction because platelet count depends on many factors, including the type of cancer, type of treatment -- particularly the type and dosage of chemo -- and a patient's general state of health. One thing to keep in mind is that a patient's platelet count generally won't drop immediately after chemo; it usually takes a week or two. This is because chemo doesn't kill off the platelets already in the bloodstream, which are mature and aren't dividing rapidly. It kills off the cells forming in the marrow, and therefore there's a delayed response, with the lowest platelet counts (called the nadir) usually occurring seven to 14 days after chemo.

After that, a patient's body will begin regenerating platelets at a rate of approximately 10 percent a day. (Platelets have a life span of eight to ten days, so, on any given day, approximately 10 percent are being lost and replaced.) But some types of cancer and some types of treatment suppress the production of platelets, so the rebuilding process can be much slower.