Hi MsMoose,
A doctor familiar with thalassemia would have been tipped off by the jaundice. Jaundice is not a sign of iron deficiency, but is quite commonly found in all types of thalassemia, including minor. Using hemoglobin level or hematocrit only cannot diagnose iron deficiency if thal minor is also present. Only by running a series of tests called an iron panel, can iron deficiency be properly diagnosed. Jaundice is a feature of thal because the small defective red blood cells that are noted in blood tests, break down more quickly than the normal RBCs. This can cause enlargement of the spleen and an increase in bilirubin production, which in turn causes the yellow jaundiced look. I would suggest refusing anymore iron supplements until you have a clear diagnosis that tells you if she is or isn't a thal minor, and an iron panel has been performed, so her true iron levels can be measured. Iron supplements can be quite harmful when taken over extended periods and not needed. They should never be taken unless an iron panel has been run.
In addition to the CBC, a hemoglobin electrophoresis test can detect beta thal minor in most carriers. Folic acid and B vitamins are among the supplements recommended here for thal minor, as these nutrients are essential for producing RBCs and thal minors have a higher than normal turnover of RBCs, which depletes these important nutrients.
I would like to see the relevant reports from her blood tests. This would include Hb or hematocrit, MCV, MCH, RBC and RDW. Any comments about the size shape and color of the RBCs is also helpful. Terms like microcytic and monochromatic are often used to describe the smaller RBCs observed in the test. These results can be used to determine if thal is present and the electrophoresis can confirm this. I will be quite surprised if she isn't a thal minor, like her father.