Hi Melsgal,
You need to have a set of blood tests called an iron panel run before you take anymore iron. Any doctor prescribing iron to a thal minor without running these tests is being irresponsible and ignoring that iron cannot improve the anemia caused by thal minor. Iron deficiency can coincide with thal minor, but this needs to be established before setting off on a course of iron therapy. The iron panel will include tests for serum ferritin, serum iron, total iron binding capacity and possibly a transferrin saturation test. Until these tests establish iron deficiency, iron should not be taken. Iron is dangerous when too much is taken and can harm the organs.
Thal minor status is usually determined by a combination of a Complete Blood Count (CBC) and a hemoglobin electrophoresis test. A CBC alone may suggest thal minor status, so an electrophoresis will be run to confirm this status. In most cases, this will be sufficient but if there is still any question, a DNA analysis can be done to determine the exact mutation and status. The confusion in the CBC can come from the fact that iron deficiency and thal minor will have similar results for some of the involved tests.