In the past, when I’ve seen serum ferritin below 50 ng/ml in a patient with low thyroid function, I would consider that level borderline low and would invariably try to raise ferritin with iron supplementation. Recently, I came across some literature that suggested that serum ferritin levels should be even higher. In fact, in one study, two-thirds of women with persistent symptoms of hypothyroidism (despite appropriate levothyroxine therapy) found that achieving a serum ferritin above 100 ng/ml ameliorated symptoms.1-3 Therefore, I’ve raised my sights and now try to increase serum ferritin to this level. Using iron glycinate for the most part, I am generally able to raise those levels slowly but surely. But even with glycinate, I occasionally will have women who have difficulty tolerating higher amounts. Therefore, I’ve doubled my encouragement of iron-rich foods. We have a nice handout on iron-rich foods that can help to reach that goal, so I will try to have a woman leave my office with this handout. I also look to give them the handouts on selenium and zinc, which are of course two other important nutrients that are often not optimal in thyroid dysfunction.
To access the IFM Clinical Practice Toolkit, log in to your account, select “My Education” from the left-hand side, then click on the IFM Toolkit tile. To find these toolkit documents, search for “Food Sources of Iron,” “Food Sources of Selenium,” and “Food Sources of Zinc” within the toolkit.