What Is Refractory to Platelet Transfusion?

Some of the people that listened to this podcast may have heard what you and I just said and said, hmm, aloe-immune refractory, not really sure what we're talking about. So let's go back to the beginning and take us through, just in general terms, what do we mean when we say that someone is, quote, refractory to platelet transfusion? What does that mean? And second, why do patients get that way? What are the general reasons?