Thyroid UK
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Could a drop in ferritin levels be causing my fatigue, headaches and brain fog?

I've been suffering from fatigue and weakness for about a year, and more recently brain fog (difficulty with concentration and focus) and headaches.

My blood tests have revealed that in the last 6 months, my ferritin levels have dropped from 98 ug/l to 37 ug/l (30-400). Red blood count: 4.57 x 10*12/L (4.5-6.5 x 10*12/L). Haemoglobin estimation: 139 g/L (130-180g/L)

Is a drop like this normal? Could this be the cause of my symptoms?

Many thanks.

2 Replies


I think you need a full iron panel (serum iron, transferrin saturation and TIBC), but don't know how easy you will find it to get it. You may be developing anaemia.

Look at the table at the bottom of this page :

It shows you what low and high levels are needed for different tests to identify different types of anaemia, but in order to use it you need a bit more information than you currently have.

Since your ferritin has dropped fairly quickly, I wonder if you have any kind of gut issues - indigestion? diarrhoea? constipation? Do you take acid blockers or antacids frequently? Another possibility - could you have a gastro-intestinal bleed? Have you noticed blood in your poo and dismissed it as piles? If you have, what colour was it (the blood, not the poo)? The darker it is the higher up the bowel/intestines it has come from. If it is bright red it probably is just piles.

You've come to a thyroid forum, so I'm guessing you know something about hypothyroidism. One of the features is a reduction in stomach acid which prevents the body from breaking down and absorbing nutrition from food, so you may have a whole series of low levels or deficiencies - the most common ones that are tested are ferritin, vitamin B12, vitamin D, folate.

Have you ever had your thyroid tested?


Have you been diagnosed with hypothyroidism already?

Low iron can be a symptom of hypothyroidism. I know a woman who didn't take any iron supplements but her ferritin levels went up to normal after she took t3.

Which, although it is a case study of just one person, strongly suggests that she needed to correct her thyroid problem in order to be again able to absorb iron in a normal way.

It seems that the body excretes any substance which might make it more energetic than it is able to be when hypothyroid, so we lose all manner of minerals and vitamins: magnesium, salt, iron, to name but a few.


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