Help with interpreting results - low T3

Hello - I wondered if anybody can help interpret my results. I had usual NHS tests back along and TSH came back in normal range 0.75 or thereabouts.

I then decided to have my T3 and T4 done privately at my surgery. I asked for the results to be posted which i got today.

Free T3 is 3.8 (lab range: 3.9 - 6.8) - lab says v sl low

Free T4 is 12.3 (lab range 11 - 24) - normal no action needed

It is the low T3 I'm wondering about - what does this mean? My symptoms are fatigue, feeling colder than most people, migraines, abdominal pains (around menstruation) and weight gain (thought his may be also to do with anti-depressants and weight gain)


22 Replies

  • Welcome to the forum, Fibro-Friendly-Zone.

    Your thyroxine (FT4) is low in range and insufficient to convert adequate FT3. FT3 is the active hormone needed in every cell of the body and the brain is a big user of FT3 which can cause depression and possibly migraine when levels are low. You are functionally hypothyroid at a cellular level despite your TSH being in the low normal range.

    Thyroid stimulating hormone (TSH) is produced by the pituitary gland to produce FT4 for conversion in the liver and kidneys to FT3. If you have ever had a head injury or whiplash your pituitary gland may have been damaged or you may have a benign pituitary turmour causing pituitary dysfunction. In these circumstances the TSH test is useless as an indicator for thyroid dysfunction. Your thyroid gland may be functional but not getting the prompts required from the pituitary gland.

    Thyroid replacement hormone ie Levothyroxine is required to restore FT4 and FT3 levels and the ideal level is the top 75% of range.

  • Thanks very much for your reply, Clutter.

    I have been trying to read up about low T3 and I found something by a specialist online who talked about Low T3 Syndrome. Maybe you are aware of it. I have been worried what I have read about Levothyroxine - not just because of what he has said but what I have heard others say. He says: "Some studies show that treatment causes harm, others show no change, and still others show an improvement. After reviewing the literature on this, I’ve come to the following tentative conclusions:

    • T4 is rarely, if ever, effective in Low T3 Syndrome and may even cause harm. This is probably due to the decreased conversion of T4 to T3 that is seen in chronic illness.

    T3 replacement has been shown to be consistently beneficial only in cardiac patients who’ve recently had surgery, heart failure or a transplant." Although he does say T3 hormone may help for 'Wilson's Syndrome' which I've not heard of before. He also says "Taking T3 when you don’t need it is potentially dangerous. It can significantly upregulate the metabolic rate and lead to cardiovascular complications in some patients.

    And, if the changes seen in Low T3 Syndrome are a compensatory adaptation of the body in response to chronic illness, increasing T3 levels artificially may have undesirable effects."

    Obviously this is out of context but I'm sure you'll see why I am worried!

    I've not had any whiplash injury though I have been taking anti-depressants for years which I know can affect the liver. It does make sense that it could be my pituitary gland. I have heard of hypopituitarism and wondered if I might have this and how would I know?

    I'm wondering what the next step is - do I go back to my GP for her to refer me to an endo? How do I know if it's a good one?

    Many thanks

  • FFZ, click on the yellow Reply button underneath the post you are replying to and the member will get an email alert.

    Show your GP your FT4 and FT3 results and follow Jimh111's excellent advice and request referral to an endocrinologist and replacement dose of Levothyroxine while you wait. email louise.warvill@thyroiduk for a list of recommended endos in your area and you can post a question asking members if they know a particular endo and request replies via private message.

    Levothyroxine is the BTA recommended protocol for treating primary hypothyroidism and hypopituitarism and is successful in treating 80% of patients. It usually has to be demonstrated that T4 monotherapy is not working before the addition of T3 is considered appropriate. I have found T4+T3 to be very beneficial for my low mood bipolar depression and stopped antidepressants 7 months ago.

    I think you're barking up the wrong tree looking at low T3 syndrome. Your FT3 is low, probably because of hypopituitarism ie failure to prompt the thyroid to produce sufficient FT4 to convert to FT3. The author really is stating the bleedin' obvious when he says taking T3 when you don't need it can be dangerous. The same is true of T4 and just about every medicine.

  • Thanks Clutter. My GP was the one who sent me the results on my request so she has seen them. I will need to make an appointment with her. I have read that Levothyroxine can be bad for the heart in some cases? I am worried because sometimes my GP can prescribe higher doses than I am happy with although she's also very willing to compromise

  • FFZ, Most GPs are inclined to undermedicate thyroid replacement rather than overmedicate. Normal replacement dose of Levothyroxine in adults under 60 with no sign of heart problems is 75/100mcg. Sadly many GPs conservatively prescribe 25mcg or 50mcg which delays recovery. Thyroid bloods will be retested 4/6weeks later to decide whether an increase or decrease in dose is required. Blood retests should follow every alteration in dose until stable.

    Over medication of Levothyroxine (T4), Liothyronine (T3) and natural dessicated thyroid (NDT) can cause racing heart, palpitations and heart thumping but decreasing dose usually corrects these. Untreated hypothyroidism can cause more heart problems than temporary over medication.

  • I used to have high blood pressure and add anxiety to the mix you can see why I'm wary about being over-medicated. As much as I hate being tired all the time, one thing even worse is feeling hyped up all the time. Last time the GP took my BP it was bang on normal. Also, I've seen some people taking Armour but that it is made up of something from the dead pig which I wouldn't want as I don't eat meat and also I've heard that NDT is also not really 'natural' as also contains ingredient from pig. Is this the equivalent to Levothyroxine? Thanks

  • FFZ, Armour and other NDT are derived from pig or bovine thyroid gland but are rarely prescribed by the NHS as use is not licensed in the UK. You would be able to decline it but it is unlikey to be offered. he Synthetic Levothyroxine (T4) and Liothyronine (T3) are the usual UK therapies. BTA guidelines recommend T4 as the therapy for primary and secondary hypothyroidism and it is unlikely you will be offered T3 unless T4 replacement is shown not to work and it is often a battle to get it prescribed either in combination with T4 or alone.

    Optimally medicated hypothyroidism should make management of blood pressure easier may also ease your anxiety.

    As you're vegetarian it would be sensible to have your B12 and folate tested unless you already supplement. VitaminD should be high in range and ferritin is optimal at 70-90 and it is worth testing as they often become low or deficient in the months prior to a hypothyroid diagnosis.

  • Thanks for that info, Clutter. The anti-depressants actually eased my anxiety very well. I'm not actually a veggie, as I eat fish, but I do't eat meat. My Vit D is still only 43 but it is moving in the right direction as compared with the other occasions.

  • Fibro-friendly-zone, my feeling is that the views of the author you quote are dubious, spurious even, and to me, read like a 6th form essay I'm sorry to say. As Clutter says, he's stating the obvious regarding the danger of taking a medicine that is unnecessary; never mind "his findings" that T3 may benefit some, may harm some, or may do nothing for others!! He's definitely wrong to say that T3 consistently helps only those with cardiac problems - there's many here who can attest to the contrary. And then he contradicts himself by saying it helps those with Wilson's Syndrome - which in fact is not a syndrome but only a concept not yet recognised by mainstream medicine. In terms of your own results, I've read that when testing for "Low T3 syndrome" the results are often inaccurate because of the methods used. Although it is often claimed that free T4 is low in patients with Low T3 Syndrome, when the proper methodology is used, free T4 is rarely low – and is often normal or even high. I'd recommend you follow the suggestions of jimh111 and Clutter :-)

  • Thanks hynoteq - the doctor's name was Dr Chris someone and he's written several articles but I didn't look into his credentials in depth!

  • FFZ, It's a good idea to post links to articles you've referenced and quoted as there are a lot of snake oil salesmen out there :)

  • Here's a link to one of his articles (Chris Kresser is his name). He's written another three or four:

  • Chris Kresser is a respected naturopath physician and he's discussing Low T3 syndrome caused by non-thyroidal illness and the potential benefit/adverse effect of prescribing T3 in those circumstances. Not the same as replacing thyroid hormone for primary and secondary hypothyroidism.

  • So do I definitely have primary or secondary hypothyroidism based on my results?

  • Welcome fibro, the guy who wrote that is NOT a thyroid specialist, he's an Acupuncturist and somebody who deals in non-science based medicine (his term is integrative medicine) and has an online shop selling supplements! The specialists are here at Thyroid UK so at least you're in the right place now. I stopped reading at the line 'T3 replacement has been shown to be consistently beneficial ONLY in cardiac patients'...!!!! I feel sorry for all the gullible people who have poured their hearts out to him in their posts.

  • Ah thanks Sazzyb - as I replied above, I didn't look too closely at the guy's credentials as I should have!

  • fT3 and fT4 are both at the bottom of their reference intervals along with a lowish TSH. This suggests an under performing pituitary. Depression can cause reduced output of TRH from the hypothalamus which leads to reduced TSH with reduced bioactivity and so lower fT3 and fT4. I would suggest an endocrinologist referral in order to rule out other causes of pituitary failure although it's quite likely your depression may be the cause.

    What you need to avoid is them saying it's due to depression so we do nothing. In this case I would recommend they give you a prescription for levothyroxine sufficient to bring your fT4 up towards the top of the reference interval. If you don't feel better they should add in a little liothyronine.

    There are cases where people suffering from depression due not respond to the antidepressants. These cases often respond to liothyronine and they are then able to manage with much lower doses of antidepressants. If this fits your situation I suggest they try you on levothyroxine first and if it doesn't work switch you to liothyronine. In which case your doctors will need to coordinate your care.

  • Thanks for your reply, Jim. I really am not depressed. I have suffered lifelong anxiety but that has been regulated by the anti-depressants which actually help more with anxiety than depression (the kind I am taking) which is why I was prescribed them. It's hard for me to know whether the a-depresants have played a part because the fatigue and other symptoms far predate the use of anti-depressants. I am also pre-menopausal so that will be a confounding variable too.

    I know these anti-depressants can mess with the pituitary eg my sister had a drug-induced hyperprolactinanaemia but they didn't test for that as far as I can see when I had the standard batch of tests a few months ago. My Vit D was low but higher than last two occasions and my differential white cell count was low but GP said no action needed.

  • OK. I replied last night after the footie, I forgot to say that hypothyroidism is a cause of depression. I guess the important point is to get your central hypothyroidism (as I believe you have) treated and then the situation can be reassesed. You may then be able to reduce or come off other medications.

  • Thanks - I guess my symptoms now sound more like depression but I always used to be the opposite, anxious, jittery, skinny build etc. I think I used to hyperthyroid if anything.

  • I'm happy that you're not depressed, you will know. I was just going by you being on antidepressants. I always found that when I was hypothyroid I was very irritable which I put down to poor clearance of stress hormones and frustration at not being able to think clearly.

  • Yes, perversely, anti-depressants can help people with anxiety and panic attacks etc (sometimes more than they actually help with depression). They can also help with many other conditions as you're probably aware