Iron is a metallic element that is vital to most living organisms. The National Institutes of Health Office of Dietary Supplements reports that nearly two-thirds of the iron in your body is incorporated into hemoglobin, the oxygen-carrying protein found in your red blood cells. Iron serves as a co-factor for energy-producing enzymes located in the mitochondria of your cells, and it is needed for normal growth and cellular differentiation. Despite its importance to your well-being, too much iron can interfere with the function of many of your organs, including your thyroid gland. Ask your doctor if you need additional iron.
Your thyroid gland is located in the front of your neck. Its sole purpose is to secrete hormones – primarily triiodothyronine, or T3, and thyroxine, or T4 – which regulate metabolism in the remainder of your tissues and organs. However, your thyroid does not function independently. The secretion of T3 and T4 is controlled by your pituitary gland, which releases its own hormone, called thyroid stimulating hormone, or TSH. If your pituitary is damaged, TSH secretion falls, and your thyroid no longer receives the “signals” it needs to perform optimally.
Certain hereditary conditions, such as hemochromatosis or thalassemia, can lead to the accumulation of excess amounts of iron in your tissues. These disorders cause iron overload by increasing iron absorption from your intestine or by necessitating repeated transfusions, which contribute additional iron to your bloodstream. According to the December 2007 issue of “Pediatric Endocrinology Reviews,” your pituitary is more sensitive to iron toxicity than many other organs and is more readily injured by conditions causing iron overload. Therefore, hypothyroidism due to iron-induced pituitary damage is relatively common in patients with these disorders.
Under normal circumstances, iron absorption from your intestine is regulated by your body’s needs. For example, anemic individuals tend to absorb iron more efficiently, as do people who are growing or exercising vigorously. The Linus Pauling Institute at Oregon State University states that iron overload due to chronic use of iron supplements is rare unless you have a heritable condition that increases your intestinal iron absorption. Thus, hypothyroidism accompanied by high iron levels should prompt an evaluation for hemochromatosis. Mayo Medical School reports that hemochromatosis affects approximately 1 in 250 people of northern European descent, and at least 1 in 10 people carries the gene for this condition.
Iron overload is most commonly due to inherited conditions, such as hemochromatosis, or repeated transfusions. Excess iron is toxic to your pituitary gland, which regulates your thyroid function. Pituitary injury contributes to low thyroid function, or hypothyroidism, in individuals with iron overload. Dietary requirements for iron vary from 0.27 mg daily for infants to 27 mg for pregnant women. Healthy adult males typically do not require more iron than is supplied in their diet. Supplemental iron should be taken only under the direction of your physician.
- Office of Dietary Supplements: Iron
- “Pediatric Endocrinology Reviews”; Endocrine Complications in Patients with Thalassemia Major; M. Toumba, et al.; December 2007
- Linus Pauling Institute: Iron
- “American Family Physician”; Recognition and Management of Hereditary Hemochromatosis; D.J. Brandhagen, et al.; March 2002