Iron and Thyroid: A Complicated Relationship
Iron and thyroid hormone are both critical components to human physiology and energy. Since they are both actively moving around the circulatory system, it is relatively easy to measure as a simple blood test to see what the levels are.
Iron is not directly measured in the blood. The clinical test we use is ferritin. Ferritin is considered the iron storage protein and can provide physicians with an indication if there is enough iron to supply the body with enough to optimally function. Ferritin releases the iron in such a controlled fashion to avoid too little iron in the body or too much. When the ferritin is low for an extended period of time, iron deficiency anemia may be present as well as other conditions.
Ferritin also plays a role in thyroid health. Many thyroid enzymatic reactions require iron as a cofactor and ferritin has been identified as an independent factor in determining thyroid health and effects of supplementation. One way is the production of T3 from T4. When we talk about active thyroid hormones these are the two typically discussed. T4 is made first and has a longer half-life, it is then converted to T3 which then does its job by maintaining metabolic rate and maintenance in addition to all its other responsibilities. The problem is that sometimes T4 instead converts to the reverse T3 (rT3) which is not considered biologically active and thus not as helpful. Several factors create this environment of T4 to rT3 conversion including stress, but ferritin has also been shown to be critical in promoting the T4 to T3 conversion.
If you are being treated for thyroid disease it is important to also consider evaluating your ferritin levels to ensure that your thyroid treatment, typically T4, can properly convert into T3. If you have any questions, you can schedule and speak with a provider who understands this relationship between ferritin and thyroid health.
Do not take iron supplementation unless under the guidance of a physician.