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Iron and Thyroid Health

Published January 28 2013

Note: Most people reading this currently take nutritional supplements, and yet most people don’t have a good understanding about the vitamins and minerals they’re taking.  Because of this, what I’ve decided to do is to write some articles which discuss the different roles of each of the vitamins and minerals in the body, and since this website focuses on thyroid and autoimmune thyroid conditions, I figured it would be a good idea to briefly discuss how they relate to thyroid health.  This article will focus on the importance of iron.

Every cell in the body requires iron.  About 65% to 75% of the body’s iron is found in hemoglobin, and about 5% to 10% is found in myoglobin.  Hemoglobin carries the oxygen to all of the areas of our body, while myoglobin carries and stores oxygen for the muscles.  This is why a deficiency in iron will usually result in fatigue.  Another 1% to 5% of iron is found as part of enzymes.  Iron is also important for optimal immune system health.

Some healthcare professionals will refer to any situation where iron is below the reference range as being “iron deficiency anemia”.  However, if the ferritin and/or serum iron levels are low but the red blood cells, hemoglobin, and hematocrit are within the normal reference range, then this person doesn’t have an anemia.  Of course iron is required for the formation of red blood cells, so if an iron deficiency isn’t addressed then over time this will lead to iron deficiency anemia.  It is also possible to have anemia without an iron deficiency.

Detecting The Different Causes Of An Iron Deficiency

When it comes to iron deficiency, it is important for someone to determine what cause of this problem is.  Many healthcare professionals automatically assume that someone who has low ferritin and/or serum iron levels needs to consume more iron.  I admittedly was guilty of this too in the past, as if someone was low in iron I would tell them to eat more iron-rich foods, and I frequently would recommend iron supplementation.  But many times an iron deficiency isn’t caused by low iron intake, and so telling someone to consume iron without looking into the reason behind the iron deficiency not only might not correct the cause of the deficiency, but it potentially can make things worse.

Before I discuss this in greater detail, I’d like to briefly talk about how to detect an iron deficiency.  Obviously one should look at the serum iron.  However, usually the first sign of an iron deficiency is detected by seeing low ferritin levels on a blood test.  Ferritin stores iron, and while the lab reference ranges are usually around 10 to 122 (in pre-menopausal women), one probably should become concerned if the ferritin levels are below 40.  This is true even if the serum iron levels look fine.  Ferritin can rise with inflammatory conditions, and so it is possible to have high ferritin levels but low serum iron levels.  Along with looking at the serum iron levels and ferritin, it also is a good idea to look at the total iron-binding capacity (TIBC) and % saturation.  The TIBC will usually be elevated in iron deficiency states, while the % saturation will decrease.

So if one has an iron deficiency, which is confirmed by low ferritin levels, and perhaps low serum iron levels, then what is the next step?  The next step is to look at the some of the potential causes.  One cause is not consuming enough iron in the diet.  But as I mentioned before, there can be other causes as well.  For example, problems with iron absorption are common.  This can be due to the body not producing a sufficient amount of hydrochloric acid, which in turn can be caused by numerous factors, such as hypothyroidism or H. Pylori.  Vitamin C is necessary for the proper absorption of iron, and so a vitamin C deficiency can cause problems with iron absorption.  Taking certain medications can also interfere with iron absorption.

Other factors can also play a role in an iron deficiency.  For example, the liver helps to transport iron from the enterocyte (an intestinal cell) to the red blood cell, and so problems with the liver can also interfere with iron absorption.  Having a leaky gut can also cause problems with iron absorption, along with other minerals.  Having a heavy menstrual cycle month after month can also lead to an iron deficiency. Taking too much of a specific mineral, such as manganese or zinc can affect iron absorption.  This is yet another reason why you don’t want to randomly take a large dosage of any vitamin or mineral.

How Does Iron Relate To Thyroid Health?

As I mentioned earlier, iron is necessary to help deliver oxygen to all of the areas of the body, and this of course includes the thyroid gland.  Iron, along with other minerals, is important for thyroid hormone synthesis.  Even though selenium is the main mineral involved in converting T4 to T3, iron also plays a role in this.  Iron is also important for the formation of cortisol, and in other articles I’ve spoken about how the adrenals can affect thyroid health.  Earlier in this article I also stated how iron is important for optimal immune system health, which is important for those people with Graves’ Disease and Hashimoto’s Thyroiditis.

Also remember that people with thyroid and autoimmune thyroid conditions commonly have hypochlorhydria, which can affect iron absorption.  So while iron can have both a direct and indirect effect on thyroid health, a thyroid or autoimmune thyroid condition can also impact the iron levels.

Food Sources of Iron

There are two forms of dietary iron.  One form is heme iron, which is about 10% to 30% absorbable and is found in foods such as meat, fish, and poultry.  Nonheme iron is the other form, which is only 1% to 10% absorbable and is found in plant based foods, such as nuts, fruits, vegetables, and grains.  So heme iron is more absorbable, which is one reason why vegetarians are more susceptible to having an iron deficiency.  Dairy products also have some iron, although it’s a very small amount and is poorly absorbed.

Supplementing With Iron

As a reminder, one needs to be careful when supplementing with iron.  This of course is true with the other minerals as well.  The RDI for iron for premenopausal women is 18mg/day, and 30mg/day in pregnant women.  Men and postmenopausal women usually don’t need to supplement with iron, although of course there are exceptions to this.  The RDI is 8mg for men and menopausal women.

Iron Toxicity

One needs to be careful when supplementing with iron to avoid a toxicity problem.  One usually will need to consume a larger dosage (75 milligrams or greater) per day for awhile before there’s a risk for a toxicity.  Hemochromatosis is when there is too much iron in the body.  Frequently the cause is genetic, which is referred to as “primary hemochromatosis”.  This is when the person absorbs too much iron in the digestive tract.  Acquired hemochromatosis is less common, but is still something to be aware of.  Severe iron load is a serious problem, as it can lead to organ failure, and in some cases even death.  And not everyone with hemochromatosis will have overt symptoms, and so doing the proper testing is essential.

So hopefully you have a better understanding of why iron is important.  Iron plays a major role in the formation of red blood cells and in oxygen transport, and this is why a deficiency in iron frequently will lead to fatigue.  Iron deficiency can also affect thyroid health, but a thyroid condition can in turn affect the iron levels.  Perhaps the most important point to remember is that just because someone has an iron deficiency doesn’t mean they should supplement with iron, as it is important to try to determine the cause of the deficiency.