EOS refers to the count of eosinophils, one of the white blood cell types. You'll see the EOS count, usually as a percentage, in a
Differential blood test, which is sometimes performed along with a
Complete Blood Count (CBC).
Depending on who you ask, the normal EOS range is 0% to 5%, 0% to 6%, or even 0% to 8% of white cells. Elevated eosinophil levels in the general population can indicate allergic reactions or the presence of parasites. Eosinophilia is the condition of having a high EOS concentration.
There is a very good
description of eosinophils and their actions (written for asthma patients) by the Midlands Asthma and Allergy Research Association in the U.K.
Because eosinophils develop in the bone marrow, they are affected by bone marrow failure. You'd hope to see perfectly normal counts a year after transplant, so it's not unreasonable to have concerns and to ask the doctors more questions about it. There may not be many statistics about continuing high EOS counts for adolescent post-transplant AA patients, but the doctors should explain whatever they
do know.
Does "monitoring the situation" mean getting regular differentials to keep an eye on Danica's EOS and other white cell percentages? You might ask the doctors at what point they would consider an elevated EOS to require more than waiting and watching?
Have any other of Danica's blood counts been unusually high or low?