Blood test interpretation for iron levels

Patient: My wife has iron-deficient anemia due to removal of most of her large intestines. Her hematologist in NJ told her the signifying factor was serum feritin levels but the doctors here in western PA tell her the signifying factors are hemoglobin levels. She has routinely had to have iron infusions (from NJ doctor) and is showing the symptoms (excessive fatigue, weakness, pale and clammy skin) that her NJ doctor used as an indication that she needs an iron infusion. If her hemoglobin level was tested last week at 12, what should a normal feritin level be? Also, what is more signifcant, the hemoglobin or feritin levels?