Thal Minor Tests help please

Hi, My son is 5 and although his doctors haven't mentioned it, a dietician said I should rule out Thal minor based on his labs.
Any advice would be appreciated.  I don't know if this is typical of Thal Minor or not...

His Hgb was low- 10.8 and went up to 11.7 after 8 mos. of low dose iron supplementation.
His Hct was 34 and now at 36 after supp.
Ferritin went from 20-28.
Iron, Iron Sat, TIBC  all normal.
Everything else normal (rest of cbc, metabolic panel, etc).

He has some food intolerances that we have recently figured out and they caused him GI issues.  I (and dr.) assumed that his levels were low because he wasn't absorbing iron well as all his food used to go right through him

Doctors are concerned that his Hemoglobin, etc may drop again now that we've stopped the fer-in-sol iron supplement.  I think because his HGB didn't rise all that much with the supplement (although he was on a pretty low dose).

What labs are usually "off" with Thal minor?   Also, is this something that is routinely checked for on prenatal tests?  I'm wondering if I should call my OB to see if I was tested as a carrier.
Thanks so much!!

To know a person has
thalassemia minor or not,
through the HGB is not enough.
To determine accurately, go
through hemoglobin
electrophoresis test. If you want
to know the past can actually
complete blood count, although
not 100% accurate. Indication if a
person has a low MCV and
MCH, but not low HGB and HCT
can be sure he has thalassemia
minor. What about your son MCV and MCH values​? You should
show the results of a complete
blood count your son here.
About your son a low HGB, it is
because of iron deficiency. You
son have a low ferritin. Best wishes.

The electrophoresis test can reveal what the CBC can't. This should be done because you don't want to continue treating anemia from thal minor with iron, if thal is the reason for the anemia. It is possible to have both and once the iron deficiency is corrected, the iron supplements should stop.