With these readings it is possible that your son is intermedia and that the early low reading was due to a temporary drop in Hb. I think it is still too early to tell for sure and that only with some more time and observation of his Hb levels, can it be determined whether he is major or intermedia. For the time being, be thankful that his Hb level has maintained and that he hasn't yet required a second transfusion. If he does maintain an Hb of 6-7, he will most likely be classified as intermedia.