HU is short for hydroxyurea or Hydrea. It is in pill form and suppresses blood cells, including platelets. Her doctor changed her to interferon due to her young age and needing to take the meds the rest of her life. Do you know if your son has the JAK2, CALR or MPL gene mutation? My daughter had no symptoms. High platelets were found during routine blood work. I was worried sick to begin with. I have connected with several people with this disorder that are living “normal” lives. Again, the best to you and your son.