Thyroid and Iron Deficiency

Your iron status is extremely important when it comes to thyroid health. If you are feeling fatigued and have any issues with your thyroid – an iron deficiency may be the cause.

First thing’s first let’s learn a little bit about an iron deficiency. There are so many different terms such as “iron deficiency anemia,” “iron deficiency” or “anemia.” So what is the difference?

Iron Deficiency: this is when we have low iron levels.

Anemia: this is when hemoglobulin levels are low. Hemoglobulin is the protein in your red blood cells that carries oxygen to all organs and tissues in the body.

Iron deficiency anemia: this is when we have low iron levels along with low hemoglobulin levels.

Okay so now that we have got that cleared up, let’s see how the thyroid is connected here.

In hypothyroidism we see high Thyroid Stimulating Hormone (TSH) and lower T4 and T3 hormones. Remember, T3 is our active form of the thyroid hormone, it is responsible for all functions of the thyroid such as temperature regulation, mood, energy, metabolism etc.. T3 hormone is created from T4. Nutrients required for this conversion include iodine, iron, tyrosine, selenium and zinc.

Symptoms of hypothyroidism include:

  • fatigue
  • intolerance to cold temperatures
  • constipation
  • dry skin
  • brittle nails
  • weight gain
  • changes in voice – increased hoarseness
  • muscle weakness

When you have lower thyroid hormone levels (ie. T3 and T4) in hypothyroidism this can suppress the creation of red blood cells in the bone marrow. Research indicates that the prevalence of anemia in hypothyroidism is 43% compared to 26% in the control group (no hypothyroidism)1.

Additionally, researchers have found that patients who are iron deficient who were treated with iron for 12 weeks showed improved values of total T3, total T4 and Free T4 concentrations2. Therefore showing us that treating an iron deficiency can really help thyroid hormone levels.

Lab testing to consider:

  • Complete Blood Count (CBC)
  • Ferritin
  • Thyroid Stimulating Hormone (TSH)
  • Free T4
  • Free T3


As naturopathic doctors, we can assess your lab work and your lifestyle (ie. energy, sleep, stress, diet etc) and determine which type of iron would be the best fit for you.


  1. Eftekhari, M. H., Eshraghian, M. R., Mozaffari-Khosravi, H., Saadat, N., & Shidfar, F. (2007). Effect of iron repletion and correction of iron deficiency on thyroid function in iron-deficient Iranian adolescent girls. Pakistan Journal of Biological Sciences : PJBS, 10(2), 255–260.
  2. Mehmet, E., Aybike, K., Ganidagli, S., & Mustafa, K. (2012). Characteristics of anemia in subclinical and overt hypothyroid patients. Endocrine Journal, 59(3), 213–220.