What to make of low ferritin, normal iron
I’ve been getting a number of lab tests back that show a low ferritin and a normal iron profile and hemoglobin. What should I do to monitor these patients? Do they need any treatment? Adam Gavsie, MD, Westmount, QC
It’s difficult to answer this question without seeing the actual results of ferritin, iron profile, hemoglobin and red cell indices, but these general statements may be of help:
- In the sequence of events leading to iron deficiency anemia, the fall of serum ferritin is the earliest manifestation of iron depletion, the fall of serum iron and iron saturation appear next and then anemia develops.
- In partially-treated iron deficiency anemia, serum ferritin remains low when hemoglobin and serum iron have returned to normal. Ferritin returns to normal when iron stores get repleted with further iron therapy.
- Besides iron deficiency, there are two other conditions that are associated with low serum ferritin. One is hypothyroidism and the other is scurvy.
- Some patients with iron deficiency may complain of tiredness, even if they aren’t anemic. If the patient with low serum ferritin is complaining of tiredness, you could treat him or her with iron to see whether the tiredness improves.
- The workup of a patient with low serum ferritin which represents iron depletion without anemia is the same as that of iron deficiency with anemia (e.g.: complete GI investigation if the cause of anemia isn’t known).
- Variation in daily serum iron is high. There’s a significant diurnal variation in serum iron, levels being the highest in the morning and lowest in the evening.
- Serum iron goes up following ingestion of iron-containing foods; but serum ferritin does not.