So we all know how rubbish it feels to be iron-deficient, but did you also know how rubbish it can make your thyroid run?
It can actually be a large reason as to why someone may be treated with thyroxine for their underactive thyroid, and still feel the symptoms.
iron deficiency could be the missing link.
Let’s explore the pathological dance between the two.
Iron deficiency interferes with the normal functioning of the thyroid.
And just a quick refresher - T4 is the thyroid hormone our body makes, and it then converts over to T3. T3 does all the working on our cells, telling them how fast or slowly to run and so on.
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To make T4, our body has an enzyme called thyroid peroxidase that needs iron to work. Iron is needed for the conversion of iodide into the active iodine which is used to create T4. This activity is very dependant on iron.
In iron-deficiency, this enzyme’s activity is reduced so your T4 levels could drop. -
Some studies have suggested that the reduced oxygen carrying capacity in iron deficiency inhibits the conversion of T4 to the active T3 thyroid hormone.
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Iron deficiency also appears to reduce T3 being able to bind to cells, so it cannot exert it’s effects on the cell itself. With that, comes along all the classic symptoms of sluggish thyroids I.e slow metabolism.
Iron-deficiency anaemia and sub-clinical hypothyroid
On the flip side, if you have iron-deficiency anaemia, and sub-clinical hypothyroid - the thyroid concerns will make it all the harder to fix the anaemia. This is because of…
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reduced T3 levels in hypothyroidism down-regulates ‘iron-regulatory-protein’ which slows down the production of ferritin by the liver.
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In simple terms - you could be supplementing with iron, but this pesky ‘iron-regulatory-protein’ has been slowed down because of the thyroid, meaning the iron you are bringing in isn’t being stored as ferritin by the liver.
So your ferritin levels may not budge on blood tests.
Thyroid hormones stimulate ‘erythropoiesis ‘
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- the production of red blood cells (haemoglobin). Low T4 and T3 results in reduced red blood cell levels creation contributing to anaemia and all of the horrible symptoms that come along with it.
