High ferritin, but low t3: Hi there 👋 I've been... - Thyroid UK

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High ferritin, but low t3

Rkx212 profile image
17 Replies

Hi there 👋

I've been on dual therapy for the last few years for hypothyroidism, with a stable dose of 25mg t4 and 70mg of t3 (yep, that's not a therapeutic dose of t4 but it keeps them happy 🤷)

My recent annual blood tests came back as borderline under on my t3 levels (2.2, range 2.4-6.0). T4 & TSH suppressed as expected. (In 2021, t3 4.4 with same range).

So they decided to repeat, with additional tests. The t3 is still the same (2.4 same range) but my ferritin is high (214, range 7-150). Everything else is in the normal range (fbc, fasting glucose, urea&electrolytes, cortisol, vitb12, folate, LH, FSH)

I haven't taken any supplementation for over a year, and my diet is not high in iron.

Now I'm terrified that they're going to decide my higher ferritin means I'm over medicated and reduce my t3, even though its showing as borderline - and my fatigue and weight gain in the last 8months are in line with under medicated.

Does anyone have any thoughts as to possible cause or link to higher ferritin? TIA.

17 Replies
SlowDragon profile image

Was test done as recommended

Early in morning, before 9am and last dose levothyroxine 24 hours before test..

Day before test did you split T3 and take last 1/3rd or 1/2 of daily dose T3 approx 8-12 hours before test

High ferritin

How old are you….pre or post menopause

Do you have autoimmune thyroid disease?

High ferritin can be caused by inflammation of having Hashimoto’s

High ferritin doesn’t necessarily mean you also have high iron

Medichecks iron panel test


Rkx212 profile image
Rkx212 in reply to SlowDragon

Thanks for the reply...

Bloods at 10am, which is the earliest it can be done in my local hospital & is consistent each time I get it done.Last T4 was 27hrs before.

T3 is split 60%/40% morning/evening and last dose 15hrs before.

Which is consistent with the past few years worth of tests.

Pre-menopausal (& LH & FSH levels were good)

I know I'm autoimmune hypo - after private bloods done for antibodies - but nhs have never taken that into account.

I'd been reading high ferritin can be from acute and chronic inflammation - so it would fit with autoimmune, it was just the hyperthroid link was more well documented.


SlowDragon profile image
SlowDragonAdministrator in reply to Rkx212

So you (or your GP) should do full iron panel test to check if iron is also high

greygoose profile image

So, I take it you didn't have CRP tested at the same time as ferritin? Always a good idea to do the two together, because - as you said - high ferritin can be due to inflammation, and CRP is an inflammation marker.

How do you take your T3? Do you always take it on an empty stomach, well away from food, other medication, etc., just like levo? It's incredible to have such a low FT3 when taking 70 mcg T3.

Rkx212 profile image
Rkx212 in reply to greygoose

No CRP done. I don't think they were looking for inflammation specifically - they were looking for a reason other than thyroid for the fatigue (hence the ferritin, Vitb12, cortisol) .Thyroid meds always on an empty stomach, at least 1hr before food. No other meds, and when I was taking supplements (over a year ago since I fell away from that routine) I made sure nothing was near either the thyroid meds or another supplement that could interact.

I'm gluten free & very low dairy.

Trying to do everything right.

greygoose profile image
greygoose in reply to Rkx212

I'm sure you are, but sometimes it's not easy to know what is right.

It really does beggar belief that with an FT3 that low, they are looking for 'other reasons' for fatigue. That, in itself, would account for it. So, I would have thought the first course of action would be to find out why your FT3 is so low, given the dose you are taking. It's got to be a problem in the gut - leaky gut or low stomach acid or something.

Rkx212 profile image
Rkx212 in reply to greygoose

I'm now wondering if the 3month course of doxycycline I had to take has affected the results, due to possible change to gut biome. The increase in fatigue started before, but the blood tests were done during and 2wks after I finished the course.🤔 I was trying to take pre/probiotic to help but I was so nauseated for the entire course, if was hard to take anything.

greygoose profile image
greygoose in reply to Rkx212

How high was your FT3 before the doxycycline?

Rkx212 profile image
Rkx212 in reply to greygoose

Past 3years of annual checks were mid to upper range of normal (5.4-4.4) - gradually decreasing, at same dose.

greygoose profile image
greygoose in reply to Rkx212


Is that the range, or the results? If results, what is the range? Because even they look low compared to your dose.

Rkx212 profile image
Rkx212 in reply to greygoose

That's the results. The range is 2.4-6.0

greygoose profile image
greygoose in reply to Rkx212

OK, so that's an unusual range. The results were higher than one thinks. This is why we always need ranges with results.

It is a big difference, then. When one sees differences like that, the normal reaction should be to retest, because errors do occur in testing. I'm not an expert on the subject, but I doubt the doxycyclin could be responsible for such a big drop.

ConstantResearcher profile image

As I understand it ferritin are your iron stores….not your available iron. So I would check actual iron levels. And your body might put iron into ferritin storage when trying to pull iron and keep it from feeding a potential infection for example H pylori. H pylori eats iron so as a defense mechanism your body might put your iron into ferritin storage to keep it from feeding it. So, high ferritin could also mean something like that…..wouldn’t hurt to do a GI map (although expensive) to check for gut infections.

Rkx212 profile image
Rkx212 in reply to ConstantResearcher

Thanks for the reply.I'm wondering if the 3 month course of antibiotics I had to take all of Feb, March, April (eye condition) would of affected the gut biome - to reduce t3 absorption? Could 3months of doxycycline affect ferritin storage?

Luisa317 profile image
Luisa317 in reply to Rkx212

No, doxicyclin it effects to your gut biome and if you got leaky gut and messed your biome the body shuts your iron storages down to preserve it. That is why your ferritin shows too high even though your iron might be low. I would retest ft3 and iron to see what is really going on.

humanbean profile image

High ferritin may be indicative of inflammation somewhere in the body. People with poorly treated thyroid disease often suffer from inflammation. If you had an iron panel done it might show low levels of iron in the blood.

High ferritin, low iron, and low in range or under range haemoglobin when found together are indicative of a condition called Anaemia of Chronic Disease, which is found when inflammation is a problem. For info on this condition :


If your problem is another form of anaemia you may find this link of use :


The best private iron panel I know of is this one, and it is a finger-prick test :


Discount codes for testing companies can be found on this link:


headfort profile image


Has anybody mentioned hereditary hemochromatosis. My ferritin levels suddenly

spiked up 7 years ago at 67 on a routine check for my thyroid. My ferritin was always under 50 but

it read 186 on this occasion. Two months later it was up at 286 so my doctor took

action. I don't to this day know which side of my family had the condition as my parents

had passed away.

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