Thyroid UK
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I've just got my latest ferritin result and it is still too low - 25 ug/l (range 12-250 but I understand it really needs to be above 50). Over the past several years I've had it tested several times and it has varied from 18 to 38. I've been taking iron supplements for several years - 15-18 mg/day for most of that time but for many months now I've increased that to 30 mg/day (as iron picolinate) so was hoping that would improve my levels but apparently not. My multivitamin also contains 667 ug of folate (half as methylfolate and half as calcium folinate) and 133 ug of B12 (half as methylcobalamin and half as adenosylcobalamin) amongst other things.

I've recently switched to NDT and my latest thyroid results are:

TSH 0.47 mIU/l (0.27-4.2)

FT4 16.4 pmol/l (12.0-22.0)

FT3 4.4 pmol/l (3.1-6.8)

Other results that might be relevant:

HCT 0.398 (0.33-0.45)

MCHC (g/l) 352 (300-350)

Red cell folate 1486 nmol/l (285.4-1474.7)

Active B12 111 pmol/l (25.1-165.0)

Methylmalonic acid 0.10 umol/l (<0.29)

Homocysteine 10.10 umol/l (<15, desirable <10)

25 OH vitamin D 92 nmol/l (50-200)

I do have very heavy periods, which is the most obvious reason for chronic low ferritin but can anyone tell me whether any of these results suggest there might be anything else going on?

Should I increase my iron intake even further?

Should I switch to a different iron supplement and which type is best?

6 Replies

Calluna, ferritin is optimal halfway through range and certainly needs to be around 70-90. I think I've read that low iron can cause heavy periods but I may be wrong. Heavy periods will certainly cause low iron and that may be why ferritin is low. Try 60mg iron and take it with 500mg-1,000mg vitamin C which aids absorption and minimises constipation.

FT3 is low in range. FT4 very good. TSH is low but it's often suppressed on NDT. If you feel well stick with your current dose. If you are symptomatic increase dose by half a grain (30mg).

Active B12 and vitD are good.


Hello Calluna,

You did well making the switch to NDT with low iron as many fail to be able to raise to optimal dose.

I would think if you have been trying to supplement iron for several years without success, there must be other deficiencies that perhaps iron requires to be able to absorb.

Active B12 is a good level but I think other B's work with iron too.

Perhaps try supplementing a good B complex and of course Vitamin C (with bioflavonoids and rosehips are best).

Also being hypothyroid can result in a lowered production of stomach acid which in turn leads to the malabsorption of iron. I supplement Betaine Plus with pepsin.



Definitely up your iron. Try Ferrochel or Ferrous fumerate and plenty of red meat. It will be the heavy periods I think causing it, though maybe you have an underlying absorption problem too.

Have you ever tested for celiac? Cheap online tests available, worth excluding. Up to one in 20 hypos have it. If you are already completely off gluten discount that suggestion. GP might agree to test y ou if you point out that your iron level is stubbornly refusing to rise and the overlap with hypo.

Do you have any other gut symptoms, other than constipation?


I had problems raising my iron. I was taking ferrous fumarate 210mg (available from some pharmacies in boxes of 84, without a prescription, and it doesn't cost a lot) for nearly two years to get my ferritin up to mid-range. I only succeeded in the end when I went gluten-free which improved my absorption rate.

Each tablet of ferrous fumarate 210mg contains approximately 210mg of ferrous fumarate + fillers - stay with me, there is a reason for apparently stating the obvious. The amount of actual iron (elemental iron) in each tablet is approximately 69mg. So if the maximum dose is taken (1 tablet, three times a day) there is a total of 207mg of elemental iron in the 3 tablets taken.

The maximum dose of elemental iron that should be taken from any kind of supplementation per day is roughly 200mg per day. Some people can't tolerate this much though because iron supplementation is rough on the gut - it's irritating, causes dreadful constipation, and makes some people feel sick.

The vitamin C suggested by Clutter helps enormously with the constipation. Building up to maximum dose of iron supplements over a couple of weeks also helps the gut to adjust.

Some of the more powerful iron supplements are :

ferrous sulphate - the least well tolerated of any iron supplement I know.

ferrous fumarate - the one I used. I did adapt to it after a while, but many people can't take it.

ferrous gluconate - never tried it personally

Some of the lower dose iron supps available :

ferrous bisglycinate or iron bisglycinate e.g. Solgar Gentle Iron

floradix - I know there are multiple kinds and I don't know which one(s) contain iron

spatone - water containing iron - each sachet contains 5mg of elemental iron. It won't raise levels much for many people.

And just for interest, this is what the British National Formulary has to say about iron supplementation and the options available in the NHS :

Anyone taking iron supplements should get tested regularly to make sure they aren't taking too much. In your case, since you absorb it so badly, I think testing only needs to be done every 6 months. But for anyone who doesn't know how fast they absorb iron re-testing should be done after 3 months. Since iron is poisonous in overdose getting re-tested regularly is not optional.

Please read helvella's post on this thread :

He has some excellent suggestions on other ways to get iron and ferritin levels up, by taking haem/heme and/or ferritin.


I have been taking Spatone for the last few days. It is well tolerated and no stomach ache. It is water in satches from Wales.The tablets all gave me stomach ache. Read up on it. It costs me $24 here in Oz.


Thank you all for taking the time to reply. There's some real food for thought here. I will definitely increase my iron supplements. My multi-vit has the full range of B vits in it, except choline which I take separately. It also has vitamin C and I take extra in a rosehip supplement (as well as getting lots in my diet).

That's really interesting about it being difficult to raise to the correct dose of NDT with low iron. I feel much better on the NDT compared with thyroxine but I still don't feel great. I'd like to get my FT3 up further. I'm only taking 0.75 grain (I was previously on 75 ug thyroxine) but I can't tolerate any more than 0.25 grain at a time (I get unpleasant hyper symptoms if I take 0.5 grain in one go - breathless, fatigue especially of leg muscles, hot flushes and uncontrollable appetite!) so I currently take 0.25 grain every 8 hours. My FT3 of 4.4 was taken about 5 hours after my morning NDT dose so that is probably about the peak of my FT3 level (I didn't want to skip the dose before the test because I never go more than 8 hours between doses so I thought that wouldn't give me a clear idea of what levels I'm getting to). My temperature, blood pressure and pulse rate have all improved since starting NDT (and adrenal support) but they are still on the low side - my temperature ranges from 35.5 to 36.5, my blood pressure is usually around 90-100 / 50-60 and my pulse is around 60 (and sometimes my blood pressure still drops into the 80s and my pulse to mid-50s). I think I will try adding an extra 0.25 grain so I'm taking it approximately every 6 hours and see how that goes (it's going to be a challenge keeping enough of a gap between all the NDT doses and the extra iron!)

I've been focusing on how much iron I'm taking and how much I'm losing but I think that's a good suggestion to look at absorption issues. I have tested negative for celiac and I've since gone gluten-free anyway. I used to have a lot of heartburn but it stopped completely when I adopted the paleo autoimmune protocol (which I've now toned down to a slightly modified standard paleo diet). I used to have chronic urticaria, which I understand is associated with increased intestinal permeability and some other irregularities in the gut (increased mast cells and histamine release similar to the changes in the skin) - I no longer have the skin symptoms but don't know if that means my gut is back to normal or not. I have some mild bloating but other than that no gut symptoms except mild constipation when my thyroid is being particularly sluggish but it's not normally a problem because I eat so much fruit and veg. I also had a month on antibiotics at the end of last year so my gut flora is likely to be pretty depleted (I'm taking lots of probiotics). As well as iron, I was also deficient in iodine despite eating lots of fish and supplementing 100 ug/day in my multi-vit (I now take 500 ug/day) so it does sound like I might not be absorbing things very well. I will look into supplements to aid digestion.

Thanks again for some really useful advice.


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