I am a Hematology supervisor and a Med tech like your dad. I have seen severely low platelet counts in viral illnesses. You can see that in leukemia, but instead of being mildly elevated the white count is usually severely elevated. Hemophilia is a disease of the clotting factors, not of platelets, so I don't think that is it either. My guess is a viral illness, but they will probably call it ITP or Idiopathic thrombocytopenia purpura, meaning they don't know why. They may give him steroids to boost his platelets. One of my good friend's 2 year old daughter had this several years ago. She was hospitalized for a couple of days, then we drew her blood every week to monitor her platelets. They eventually corrected themselves and she is a very healthy 7 year old now. My only question is how did they draw the blood. In an infant, the blood is quite often draw as a finger poke which can enduce clotting in the tube prior to running the sample. This would severely lower the platelet count prior to running the sample and every thing would be ok in your son.