Low iron can cause fatigue in women, and reasons why this treatable condition is so often missed

There’s a lot of reasons why someone may complain of undue fatigue, but there’s a few things that tend to recur. One thing worth looking out for, especially in women, is iron deficiency. Monthly blood loss is a major risk factor for this, obviously, especially if coupled with a diet low in properly iron-rich foods such as red meat and liver. It’s a common problem, and one that is often easily resolved. The problem is it tends to go unrecognised.

A fundamental reason for this, which I describe in this blog post, is that we doctors tend in women to think that fatigue is often caused by anaemia (low levels of the red blood cell pigment haemoglobin that carries oxygen around the body and delivers it to tissues). So, when we see a woman of childbearing age, anaemia is often thought of. Often, though, a blood test will not reveal anaemia as defined by ‘normal’ blood levels.

The normal range of haemoglobin is lower in women than in men. One reason for that might be that women of reproductive age are generally losing blood each month. I remember one of my tutors questioning the wisdom of having a haemoglobin normal range for women lower than that for men. He suggested that we might be simply letting many women be ‘a bit anaemic’.

But even leaving this (I think, valid) thought aside, another problem with checking for anaemia only is that iron deficiency can occur in the absence of anaemia. So, while iron deficiency is a very common cause of anaemia (especially in women), just because a woman is not anaemic does not mean she is not low in iron. And iron deficiency, even in the absence of anaemia, can cause fatigue and other symptoms such as low mood.

Because of this, it makes sense to check for iron levels too. There are several iron-related tests, and the one I’ve found to be most useful for judging overall iron levels in the body is something known as the serum ‘ferritin’ level. However, even when this test is done, we have other problems relating to its interpretation.

This issue relates again to the concept of ‘normal ranges’. Generally, normal ranges encompass 95 per cent of people. That means to have a ‘low’ or ‘high’ reading someone has to be in the bottom or top 2.5 per cent of the population. Some might argue (as I would) that this means to be ‘abnormal’ you have to be really very abnormal, and maybe it would make sense to make the ‘normal’ range narrower.

The normal range for ferritin in women is often about 12-150 ng/ml. That looks quite wide, doesn’t it? Someone with a ‘normal’ ferritin of 12 or 20, say, will still be very much down the low end of the scale, and perhaps be suffering as a result of their low iron.

We do have some evidence that this indeed may be the case in the form of a study which was published this week [1]. Almost 200 women aged 18-53 suffering from fatigue were included in the study. All of them were non-anaemic (haemoglobin levels 12.0 g/dL or more) and had ferritin levels lower than 50 ng/ml. The women were treated with ferrous sulphate (the form of iron most commonly prescribed by doctors) or placebo for a total of 12 weeks.

In the women taking iron, fatigue scores dropped by about half. There was a drop in fatigue scores seen in those taking placebo too, but to a lesser extent. The greater improvement in those taking iron was statistically significant.

This study provides at least some evidence that just being in the ‘normal range’ for iron levels (ferritin) is not enough. I’ve found in practice that, as this study suggests, ferritin levels should be above about 50 ng/ml for someone to feel properly energised.

The form of the iron used in this study (ferrous sulphate) is the last form of iron I’d use in practice, though. It’s generally difficult for the body to absorb this form of iron, and it’s often irritant to the gut and often causes constipation. My preferred form of iron is actually the brand Floradix in liquid form. I find this usually does an efficient job of picking up someone’s iron levels (and energy) where appropriate.


1. Vaucher P, et al. Effect of iron supplementation on fatigue in nonanemic menstruating women with low ferritin: a randomized controlled trial. CMAJ. 2012 Jul 9. [Epub ahead of print]

33 Responses to Low iron can cause fatigue in women, and reasons why this treatable condition is so often missed

  1. Vanessa 12 July 2012 at 5:26 pm #

    As a trainee homeopathic practitioner, I have been told that many of my tutors’ prescribe the tissue salt Ferrum Phosphate 6x, which is a homeopathically prepared remedy (but not at the very dilute doses that sceptics go on about). There is therefore a ‘material’ dose of this salt which appears to be more available to the body than standard supplements, and is very effective by all accounts (including my own, as I was diagnosed with low ferritin a couple of years ago). They are available over-the-counter in Boots, Holland and Barrett and other pharmacies, usually as Schuessler tissue salts.

    Here is a link to Miranda Castro’s article about them: http://mirandacastro.com/articles/CellSalts.htm

    The nice thing is that you can’t overdose on them – the body appears to take what it needs!

  2. tess 12 July 2012 at 8:47 pm #

    THANK YOU for this! 🙂 i get so tired of people carrying on about iron overload, when so many doctors in practice are likely to find women TOO low….

  3. Karen 13 July 2012 at 6:37 am #

    Many other countries include ‘depleted’ within the iron reference range. So you have low, depleted, normal. They would treat within the depleted range. It makes a lot more sense. Why wait until someone is haematologically recorded as being ill before treating? Many patients are symptomatic (with other conditions also) long before levels fall into the low range but doctors are reluctant to even acknowledge symptoms as being a reality until haematological indicators tell them there is a problem.
    Also many patients can have normal iron blood levels but ferritin (stored iron) can be low. Again, doctors are relucant to carry out a ferritin test if the iron is normal. Makes you wonder why the ferritin test exists at all…

  4. smgj 13 July 2012 at 10:35 am #

    I have low ferritin and are hypothyroid too. I read just this week that low ferritin is a huge problem especially on t4 replacement therapy only as the body need iron in order to convert t4 to t3 and in order to utilize t3. Low ferritine may lead to a decreased body temperature as well. 🙁

  5. Penny Vinden 13 July 2012 at 2:42 pm #

    What about post-menopausal women and tiredness? Could this be an iron problem as well?

  6. Jules 13 July 2012 at 3:01 pm #

    I can recommend Floradix as well. I have used it intermittently for 20+ years. It has none of the side effects associated with prescription iron. Personally I like the taste of the liquid form, but you can mix it into juice or get it in tablet form as well.

  7. Monika 13 July 2012 at 3:40 pm #

    The bioavailability of the iron must also be considered and this also depends on sufficient intakes of Vitamin C, folate and B12. Regular blood donors bordering on anaemia are often told to ensure adequate intake of green leafy veg for this reason. Vit C enhances iron absorption. Overloading on iron supplements when other minerals are deficient can be problematic.

  8. Free Forester 13 July 2012 at 3:44 pm #

    I have been using SPATONE for a few months now. It comes in measured-dose sachets, and I find it convenient and effective.

  9. Fiona 13 July 2012 at 4:00 pm #

    Do we get the right sort of iron by eating a regular helping of liver?

  10. ValerieH 13 July 2012 at 6:45 pm #

    mmmm liver! I try to eat some weekly

  11. Rosie Pearce 13 July 2012 at 8:10 pm #

    How long would you recommend before getting levels re-checked and also do you see floridix being safe if you are not deficient there is much concern over excess iron .

  12. Jackie Bushell 13 July 2012 at 10:34 pm #

    Once again, an article that’s right on the nail, Dr Briffa.

    There’s lots of excellent information about how hypothyroids need sufficient ferritin (70 or above) for their thyroid meds to work (and Vitamin D at top of range, plus good B12 as well) at http://www.tpa-uk.org.uk. (Thyroid Patient Advocacy).

    I was one of those with very low ferritin but not anaemic. 2 Spatone sachets a day for more than a year unfortunately seemed to make little impact but Iron Bisglycinate, recommended by people on the TPA-UK forum did the trick for me.


  13. Matty Maccaro 13 July 2012 at 10:46 pm #

    Thanks, Dr. Briffa, for the mention of Floradix. After double by-pass surgery, I was so tired and folks just kept saying “what do you expect? you just had surgery”, but after 4 months I was shocked to see a very low hematacrit and asked the nurse about it. Her shocking reply was “oh all our heart patients are aenimic”, she proceeded to tell me it would be a year before I had proper iron in my blood. I bought Floradix, used it and had my blood retested
    4 weeks later, the hematocrit was perfect. The product may seem expensive, but it is such a boost to one’s energy and general feeling of well being. I was so happy to see it mentioned in this article and hope others will try it, absolutely no constipation with this form of iron.

  14. Christine 14 July 2012 at 1:56 pm #

    I had a full blood count done due to many of the common symptoms of anemia. I am also type 1 diabetic since the age of 10 and have an underactive thyroid. My results came back normal….doctor suggested I was stressed and to make more time for me…mmmmm Dr Briffa’s comments about having a reading below 50 rang alarm bells, as my serum ferritin is 27….So I have started with spatone as it was the first liquid form of iron I could get my hands on.

  15. Helen 14 July 2012 at 6:27 pm #

    I have tried Floradix, but found after only a week that it started to stain my teeth very badly, despite my best efforts with the electric toothbrush and a whitening toothpaste. After 3 weeks I gave up. The Floradix did nothing for my energy anyway. I now take iron in ascorbate form for optimum absorption. Still no improvements noted, but at least I can smile again without embarrassment!

  16. Vanessa 14 July 2012 at 6:44 pm #

    Helen, you could try the tissue salt that I mentioned in the first comment I made at the top (which appears to have been ignored by everyone so far….) As far as I am aware, it’s not necessary to take a long course and so it won’t break the bank as a bottle of them costs about a fiver. You only need to take one tablet each time, not 4 as it says on the bottle….that’s just so that people buy more!

  17. Karen 15 July 2012 at 8:01 am #

    Matty, have you had your b12 levels checked? Nitrous oxide depletes b12. If you are someone who was low to start with the symtoms can get worse after an op. Also you get anaemic with it. If I were walking in your shoes, I’d most certainly ask for levels to be checked.

  18. Heather 20 July 2012 at 2:17 am #

    Are any of these ok to take while pregnant?

  19. Penny Vinden 20 July 2012 at 11:29 pm #

    Has anyone seen the article relating high iron to Alzheimers? Here is the abstract:
    Iron is an essential metal for your health, but too much can lead to the production of free radicals that can damage neurons in your brain, along with other tissues and organs
    Excess iron accumulation in the brain is a consistent observation in Alzheimer’s disease; a new animal study revealed that reducing iron levels in the blood triggered levels of beta-amyloid, which are associated with Alzheimer’s, to return to normal
    Separate research also showed that reducing excess iron in the brain can alleviate Alzheimer’s-like symptoms in mice
    A serum ferritin blood test is a simple way to determine if your iron levels are too high; if they are, donating blood or getting a prescription for therapeutic phlebotomy is a simple solution.
    here is the url:http://articles.mercola.com/sites/articles/archive/2012/07/19/excess-iron-leads-to-alzheimers.aspx?e_cid=20120719_DNL_artNew_1

  20. Raylene 2 August 2012 at 4:09 am #

    2 years ago my newborn daughter’s PKU came back as a carrier for Hemoglobin C. This is a disease that, if you have it fully, your red blood cells don’t live as long as they should and, among other things, you are anemic. Well, she had to have gotten it from somebody and I certainly fit the bill. I have been anemic my whole life and recently seem to have had an anemic crises. I recognized that I was absolutely exhausted all the time and my legs were restless at night. When I put 2 and 2 together I started supplementing with Ferrofood, made by Standard Process, which I always use during pregnancy and it helped immediately. I have used Floradix, but I found it too expensive and not strong enough for me. I don’t have a doctor, but I spoke to one at the walk in clinic and he had no idea what I was talking about and he couldn’t have cared less, anyways. I went to the lab and asked them how to go about getting tested and they had never heard of it. So…I’ll just keep taking care of myself until my little backwoods town in the middle of nowhere catches up with the times.

  21. Sheri 3 September 2012 at 11:12 pm #

    @ Vanessa…..I have low iron usually running around 36-45, my ferritin runs around 9-13, tIBC is high 400’s to low 500’s and crp is slightly elevated at .9 – 1.2. My dr told me to take slow release iron sulfate and after 4 weeks, there is no improvement. Measurement from a couple of days ago for the iron is 36. I have fatigue and joint (mostly hip) and muscle (mostly thigh) pain as my main complaints.
    I was thinking of trying out the ferrum phosphate and found it online through Martin and Pleasant
    (schuessler’s tissue salts) or Vitacost (Hyland brand ferrum phosphate). Are these both of good quality and are there any advantages to one over the other? Thanks!

  22. Vanessa 6 September 2012 at 10:59 pm #

    Hi Sheri

    Are you based in the UK? I’m only asking as New Era Tissue Salts are fairly easy to find in health food shops such as Holland and Barrett over here for about £5 a bottle of 450 tablets. They are prepared in a 6x potency (not to be confused with 6c). (Note that you only need one tablet per dose, not 4 as stated on the bottle – this is just to get people to use them faster so they buy more!)

    Homeopath Miranda Castro has a good website which explains all you’d need to know (she is British but lives in Florida now) – http://mirandacastro.com/articles/CellSalts.htm and this link is to her pdf file about them too: http://www.mirandacastro.com/articles/documents/Castro_CellSaltHandouts.pdf

    However, wherever you are in the world, as long as the potency is correct (ie 6x) and they are produced by a reputable pharmacy, the actual brand is of no consequence! Good luck….

  23. Sheri 7 September 2012 at 7:20 pm #

    Hi Vanessa, Thanks for your reply. I am in the USA and the only place I’ve checked so far has been Walmart but I intend to go to a health food store this weekend and I will see what I can find. I am in a small town (about 15,000 people) but within a 1/2 hrs drive of a larger city if I should need to go elsewhere. I did talk to pharmacist in the hospital where I work and she suggested trying some 60 mg iron that was combined with Vitamin C to see if that would work. I had been drinking orange juice with the iron previously so I am skeptical that it would work. I will try for a few weeks though first.
    I will look at Miranda’s website later. Thanks for the info. I so want to stop having this fatigue all the time. I am otherwise a healthy 48 yr old and I eat healthy (except rarely red meat) and I really want to have more energy:)

  24. Vanessa 7 September 2012 at 7:52 pm #

    Hi again, I thought you might be in the USA! Miranda Castro’s recommendation is to alternate Ferrum Phosphoricum (Ferr phos) with Calcium phosphorica (Calc phos) as the latter aids the absorption of the iron. They are different from normal supplements as they are diluted quite a lot and are thought to act more at the cellular level, ie more subtly. If you’ve had little success using conventional supplements then tissue salts (or cell salts, as they’re more popularly known in the US) may be a better option.

    I don’t know if you drink tea with meals, but this can inhibit iron absorption from food (and coffee too, to some extent) – as I’ve never been to the States I don’t know if you are great tea drinkers like us Brits!! Also, adequate vitamin A and those of B complex in your diet are needed for the body to be able to absorb iron, so I imagine you’ve also checked this out? It’s difficult to be able to suggest much more as you have mentioned some other problems too, so as a homeopathic practitioner, I work holistically and would therefore prescribe for you as a whole person, not just focusing on the anaemia in isolation.

    Speaking for myself, I’ve found Blackstrap molasses capsules with iron (in the form of ferrous gluconate) to be very effective.

  25. Sheri 9 September 2012 at 12:21 pm #

    Hi Vanessa, I checked yesterday with the local health food store and they do not have any of these tissue salt supplements. They said they can order me some but I said I would order online first and give it a try.
    No, I don’t drink tea very much, occasionally in the winter. I do drink coffee, usually 2 -3 cups in the morning. Otherwise, I eat pretty healthfully. I eat all kinds of fruit and vegies and usually stick to either vegetarian meals or fish or chicken. My B12 serum numbers are good and I believe I get plenty of the A and B vitamins. I have tried to focus even more so on iron rich foods lately but it hasn’t helped.
    Thanks for all the info. I will give these tissue salts a try soon.

  26. dawn 28 September 2012 at 6:10 pm #

    hypothyroid sufferer who loved your article. I had a serum iron of 5 in spring and other deficiencies left untreated, then, suddenly couldn’t tolerate my thyroid hormones any more. I also have the hip and leg pain and terrible abdo muscle cramps and cannot leave my bedroom now. I am very hypothyroid now and have now reactive hypoglcemia. Breathing been bad for ages and other symptoms which were ignored. My clue I had that I needed to supplement was restless legs and adverse reaction to thyroid caused by pooling.
    Well done once again. Thank God for Drs like you and organizations like TPAuk and the Yahoo group Natural thyroid hormones ADRENALS.
    keep up good work
    I am suffering greatly due to this lack of GP education area. I am having to supplement myself as GP pretty much washed hands of me 🙁
    Well done Dr Briffa and thanks.

  27. Lorraine 23 January 2013 at 8:04 pm #

    My test results show a hemoglobin level of 12.4 and a Hematocrit level of 36.1. My doctor says that I’m not anemic, but that 18 mgs. of iron a day should do the trick. I’ve been taking 18 mg. a day for a year now, and I still feel like crap. (I bleed very heavily every month because I am in perimenopause). I’m wondering if I should be taking more iron.

  28. Dakota 25 January 2013 at 8:43 pm #

    Hi, Taking iron pills for long term is not gonna solve your problem. And iron pills will cause constipation and constipation can cause hemorrhoid. Have anyone heard of Floradix? Its a very good source for iron , its made of fruits, herbs and vegetables. No preservative, no colouring , no lactose or alcohol so its good for vegeterians 🙂 those who are allergic to gluten and wheat , ya , they do have gluten and wheat free. Taking floradix helps boost energy level so you won’t fell lethargic and helps you get through the day without the need of taking noon nap. I shan’t go on anymore. I know , cos I’m a blood donor and had been anemia after years of donating blood without replenishing my lost of iron. Do some research first and see for yourself if its worth the try. Good luck! Hope this will aid you guys in iron deficiency! Cheers to good health 🙂

  29. Sy 8 March 2013 at 12:52 am #

    Iron/Ferritin deficiency is SO common among us hypothyroidism sufferers that it’s difficult not to wonder if they are linked.

  30. Lorraine 8 March 2013 at 12:23 pm #

    I had blood work done recently, and it confirmed that I am anemic. In order for the thyroid gland to function properly, Ferritin levels need to be hovering somewhere between 70-90. Mine was 21! When I first went to the doctor, she only looked at my hemoglobin numbers and didn’t think to check my ferritin levels. I am now taking 189 mg. of iron a day to try to get my iron stores up. I’ve been reading Janie Bowthorpe’s book, Stop The Thyroid Madness, and I’ve learned a lot. In fact, it was through her website that I ordered my blood tests. I started taking the large doses of iron about a month ago. This month, my period is normal because I think my thyroid is starting to function a little better now that the ferritin levels are up. I will go back in April to get retested to see where my ferritin levels are. If you get tested, your doctor can’t just look at hemoglobin levels; he or she needs to take a look at the ferritin levels. My doctor didn’t do this, which is why I had been feeling like crapola for over a year.

  31. L 13 June 2013 at 8:11 am #

    Thank you for this article. I have had very low ferritin levels for 5 months now, normal Hb levels I’ve been taking Ferrimed and it went up one point, to 10. I have been to a homeopath who has changed the form of iron and I hope this will help. This article has at least explained why I have no energy. This is a very frustrating thing.

  32. anna 22 August 2014 at 6:04 pm #

    I find this monthly blood loss argument not right u trained very heavily and did not find periods to be the problem.I think this is a red herring.I know that antibiotics slow liver function down and wild like to know in fact I think it is the cause.


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