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Low T3 Syndrome V: Should It Be Treated with Thyroid Hormone?


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This article is part of a special report on Thyroid Disorders. To see the other articles in this series, click here.

In this final article in the series on Low T3 Syndrome, we’ll discuss whether thyroid hormone replacement therapy is an appropriate treatment in these cases.

Why T3 Levels Are Low

Unfortunately, there are few studies that have examined this question specifically, and even fewer that have explored the question of whether T4 or T3 (and which type of each) would be the best choice.

As a clinician, my primary concern is always primum non nocere, or “first, do no harm.” From this perspective it’s important to recognize that the changes seen in Low T3 Syndrome may represent a restorative physiological adaptation by the body to chronic illness.

In other words, T3 levels are low because the body is attempting to conserve energy and resources to better cope with the challenges it is facing. Increasing thyroid hormone levels in this situation could conceivably have adverse effects.

For example, the changes observed in the thyroid axis in acute illness are similar to those observed in fasting, which can be interpreted as an attempt to reduce energy expenditure and protein wasting. (1) Giving fasting subjects thyroid hormone results in increased catabolism (breakdown). (2)

In cases of chronic illness, however, it is less clear what effect thyroid hormone replacement has. The few studies that have been done produced mixed results. (3)

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.

That said, I’ve heard anecdotal reports of improvement from people who have taken replacement T3 hormone for a condition called “Wilson’s Syndrome” (which does not exist in the scientific literature or according to any mainstream medical organizations). Wilson’s Syndrome refers to low basal body temperature and other nonspecific symptoms occurring in the presence of normal thyroid hormones.

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I’ll be the first to admit that “lack of evidence is not evidence against,” and as I mentioned earlier, there’s not a lot of research on the effectiveness of T4 and T3 replacement therapy in Low T3 Syndrome. It may be that as we look into this further, we’ll discover a role for thyroid hormone replacement in these conditions.

That said, I think caution is warranted.

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.

In the majority of cases of Low T3 Syndrome, I think it’s preferable to identify the underlying cause and treat that. As I discussed in articles #3 and #4 in this series, those causes most often include infections, autoimmunity and inflammation.

Articles in this series:

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  1. In all the articles, it was never quite clear just what the numbers are for low T3; I think that would be helpful. My daughter’s free T3 is 3.1. the doc said this is sub optimal and wants to put her on a natural thyroid med with T4 and T3. From your article, I agree that i’d like to know what is causing this first. She has no chronic illness, eats healthy, very fit and loves to exercise, but is low in vit D (29) and is tired at times (but aren’t we all?). That is the only course of action I am going to take right now and see if getting the D corrected might help. I’ll then retest to see where she’s at. Other than that, I’d love to know if there is anything else we should do. Thank you!

  2. Being of southern italian descent and supposedly thyroid problems on both italian and english sides of family..my blood thyroid..,(routine tests) and cortisols are normal i have high cholesterol and bad reflux..some bowel prob. I dont have food allergies some arthritis. Good cardiac function(according to ekg and pre op cardiac stress test altho calcium test was abnml. Low to nml bp low pulse. Some signs of insulin resistance. I try to eat right..paleo/meterrain.But i have little energy now to just get thru daily chores/work as nurse(recently retired)
    But i do have symptoms of hypothyroidism…excessive wt gain 198#(5’3″) bmi 35 total body fat 29% low energy some hair loss dry skin cold lethargic/low energy/ sleepy but dont sleep well( no apnea).
    Could this be results of low free t3….HOW can i find someone to test and treat ..when my doctors say nothing is wrong you just need diet and exercise
    Chris can you please advisr

  3. Just read the series of articles – great information!! I was diagnosed as hypothyroid 20+ years ago – have been taking levothyroxine since then – now reduced to 75 mcg/day. Only “standard” thyroid testing done in the past – recently tested for antibodies – confirmed I don’t have Hashimoto’s thyroiditis. Apparently I have low T3. Also have annulare granuloma -(autoimmune/inflammatory?). Recently stopped all nightshades, gluten/wheat and have limited dairy. Have been off soy for a long time. Have started supplements to improve conversion of T4 to T3 – will undergo further testing in about a month. Since stopping all nightshades annulare granuloma has improved – maybe if this gets under control – T4 conversion might improve(?). Aside from losing hair (shampooing/brushing) and difficulty losing weight (5-10 lbs) – don’t have typical number of symptoms/problems associated with hypothyroid. Could the levothyroxine be part of the problem?

  4. If hypothyroid people have tried T4/T3 combo therapy and it doesn’t make them feel better, a trial of T3-only (or T3-only combined with NatureThroid) should be given. You never know if T3-only can help until you try it, and if it works for you it can be life-changing.

    There are only so many ways to treat a hypo condition with thyroid hormone: T4-only, T4/T3 combo synthetic, T4/T3 combo natural desiccated, T4/T3 combo with added T3, or T3-only. All hypo patients should have access to trials of *all* of the above until they find the one(s) that help their symptoms.

    It doesn’t matter what the labs say, because, as Chris points out in these articles, the labs don’t always show what’s really happening in the body, and normal/abnormal lab values can vary so much from person to person.

    Once a hypo person starts to feel better on whatever type of thyroid hormone works best for him/her, then he/she can better address underlying causes of inflammation. It’s hard to make big changes in lifestyle and diet and start complex treatment protocols for chronic infections when you don’t even have the motivation to get dressed in the morning.

    What I’ve seen from many holistic practitioners is that they try to solve the problem through diet, supplements, detox, etc., instead of giving people what they really need: *replacement* thyroid hormone.

    When you lose a lot of blood in an accident, you replace it. You don’t say: oh, I’ll just build this blood back up through diet and supplements. Thyroid hormone is as essential as blood. If you don’t have enough, it’s hard to build your body back up through food and supplements alone. It’s hard to fight any chronic infections you might have, and it’s hard for the immune system to come back online and fully function again without adequate thyroid hormone.

    Some people do *really* need T3-only, there are many personal stories on the internet about it, books about it, and doctors who Rx it who see it work miracles for some people. It doesn’t really matter what their labs say or what the underlying cause of their hypo condition is if the T3-only makes them feel better and doesn’t cause adverse side effects.

    I personally know people who feel their best on T3-only. I’m one of those people who improved only after T3 was added to my NatureThroid protocol. LDN didn’t improve my thyroid function. Going after underlying causes of inflammation didn’t improve my thyroid, it just continued to get worse, even after treating Lyme & co-infections, H. pylori, SIBO, doing detox for heavy metals, dietary changes, etc.

    I believe that sometimes the thyroid gland itself *and* the whole chain of events that occur in the thyroid hormone production & conversion cycle have somehow been INJURED and simply removing underlying causes of inflammation isn’t enough to get this complex cycle going again. Replacement thyroid hormone is oftentimes necessary, and in whatever form works best for the individual, including T3-only, no matter what the research says.

    • Those of us that used the time release T3 years ago know that it does work; it’s just not a permanent fix. As the dose goes up the body temperature also goes up. I used to do a five minute temperature check every morning, so I know. The problem is that it’s not a permanent fix, and it’s not covered by insurance. Also, the thyroid “industry” was then and is now on a vigorous anti Wilson’s Thyroid crusade which has lasted to this day. It’s obvious to me that this “crusade” has effectively stopped any meaningful study of the issue: The body produces the active T3 and the relatively inactive T4 which is converted by receptor sites elsewhere in the body to T3. Meanwhile I’m living with a low body temperature: at the gym I wear a long sleeve shirt with an undershirt; on other occasions I wear a woolen vest to keep warm. I have no hope that the industry will stand up and deal with this problem, in my lifetime (I’m 83 years old). It’s a good conversation though and I appreciate it. Also, Dr. Wlson had to learn the hard way: To really be effective the T3 has to be in a time release capsul.

  5. I used Cytomel for a total of 2 weeks for low T3. At 5mcg. I started to wake up in the middle of the night, unable to get back to sleep. Because it started a couple of days after beginning, I did not at first connect the two. At the two week mark, I was to increase to 10mcg. That night, I was completely unable to fall asleep. I stopped immediately, but that was 7 years ago, and I have never again recovered the ability to fall asleep naturally. My endocrine system is in chaos. My immune system is a mess. I have allergies and autoimmune disease, which I never had before. Any tickling of my immune system results in complete lack of sleep. Oh, and I went directly into menopause like putting your car in reverse on the highway, even though my FSH just months before was equivalent to that of a 30yo. I was a nutritionist before this happened, and my joyful life has never returned since my two-week course of Cytomel, low dose. BEWARE Cytomel.

  6. I was treated for low free T-3. For over a decade, multiple doctors had checked my TSH and T4 levels, because I was presenting with malaise, low temp, depression, irregular menses, infertility, PCOS and fatigue. Every single time the results showed euthyroid and my symptoms were shrugged off. I was told to get more exercise and stop sleeping so much.

    I finally came across a PCP that immediately recognized my symptoms and for the first time in my life, ordered free T4 and T3 to be tested. The results showed that my free T3 was very low. She explained that the treatment could be short or long term depending on the cause.

    I was started on liothyronin and levothyroxine. I had my labs checked monthly and my doses titrated. She tried armour thyroid and also compounding to get me the best result.

    After years of infertility, I finally became pregnant. After my second miscarriage, it was found that I also produced anti-phospholipid antibodies during pregnancy.

    My free T3 levels kept improving and I was eventually weaned off the replacement therapy.

    I became pregnant again shortly after and immediately was started on lovenox and low dose ASA for the entire pregnancy. My baby was born healthy.

    3 years have passed and I am experiencing symptoms very similar to how I felt before I was started on the thyroid hormones. I’m concerned that the problem has returned and wondering if I’ll find a practitioner that is willing to help.

    • Do some research on Iodine. Dr. David Brownstein has two books that might help: “Iodine why you need it” “Overcoming Thyroid Disorders”

    • Suzanne, I feel like I wrote exactly what you stated. I have been suffering with severe fatigue since giving childbirth 5 years ago. Everything comes back “normal” and I gained the diagnoses of CFS and a small degree of PCOS. I have been trying to get pregnant again with no success. Which at this point in my life I feel so bad that I don’t even feel as if I could care for another child.
      I would love to talk to you more if you wouldn’t mind. I am desperate at this point. I’m will to travel to get help, whatever it takes.

  7. Hi
    I had a partital thyroidectomy in the beginning of March this year and I’m not taking any meds. I felt fine at first but the past 3 weeks or so I’ve been very tired (even as soon as I wake up). I went for blood work and everything was in normal range even if my free T3 is on the lower end and my TSH increased from 0.73 to 2.44. The endocrinologist told me that being tired has nothing to do with my thyroid (?!) and that I should redo my labs and come in for another check up in December. Is there anything I can do to naturally increase the free T3? Would that help or should I just find another endocrinologist?

    • Hi Jennifer, I have Graves Disease and had my thyroid removed (radiated) 20 years ago. I feel best when my TSH is around 1.0 to 1.5 and my free T3 is in the upper half of the range (usually above 3.0). And you are right…your energy levels are affected by your thyroid! Best of luck!

  8. My wife has been treated for hypothyroidism for 30 years. first with Levothyroxine and now with Armour Thyroid and T3. and a lot of supplements. Some symptoms have gotten better , i.e. hair falling out, cold body temp etc. Labs are good according to doctor TSH, T3, free T3 and T4, Reverse T3 all normal. Chief symptoms are extreme difficulty losing weight despite on 1500 to 1600 balanced calories a day. constant body pain on a 7 or 8 scale. Doctor says she has adrenal Fatigue. She does show Hashimoto anti bodies. How can she be tested for LAH? Do you know any doctors in Georgia?

  9. Hi, i gave birth 7 months ago, with complications right after, with heavy bleeding and super bombarded with iv antibiotics. I got bloodwork done and my results indicate my free t3 is 2.0, which according to my doc is “mildly low, but not cause for concern”. She wants to recheck it in 3 months.
    Please can someone help me and tell me if this is bad? Thank you thank you!

  10. Doctor told me i was slow on the gas and hard on the brakes! Low T3 and high reverse T3. Was on levothyroxine for three months with natural thyroid hormone as well. Stopped the thyroid hormone for next three months but stayed on T3. At this point, my numbers are way off with exceedingly low TSH and high T4. So the doctor is mystified and has me off everything now. Symptoms haven’t changed noticeably.

  11. I was prescribed T4 after going off the pill 5 years ago. I never took it and instead pushed for more tests. I had and MRI and was told I had an 8mm tumor on my pituitary glad that had most likely hemorrhaged. I have another MRI coming up to check on that… in the mean time my new doctor is prescribing me a T3 for low T3 (all other numbers were about normal but she did not test RT3).
    ANY suggestions?!? I have not taken any thyroid medication as of yet, I am 30 and people assume I am the healthiest person they have met. I of course have mood disorders and low sex drive but everything looks fine on the outside.
    Why did my doc not want to see my RT3? How important is that?
    Should I try the drugs or hold out for more tests and answers?
    I am hoping to have a baby in the next year or two and I am trying to make sure my health is optimal.
    Any personal suggestions is greatly appreciated! This stuff can be confusing!

    • Was your MRI “WITH Gadolinium Contrast” to detect change? Please check out http://www.gadoliniumtoxicity.com many patients even those with no known kidney disease are retaining gadolinium in their bodies, it is causing fibrosis. Fibrosis is scarring within veins, arteries and organs! This has happened in my ownbody and I am suffering horribly from it and want to warn others before it is too late. Please check out this informative site.

      It is also known that the A committee of the European Medicines Agency (EMA) has recommended the suspension of the marketing authorizations for four linear gadolinium-based contrast agents (GBCAs) used for MRI scans because of concerns about small amounts of gadolinium from administered GBCAs being deposited in the brain.
      (for right now they will only be speaking to the collection of gadolinium in the brain, because in order to test for that you would have to die for them to biopsy you, but there are blood and urine tests to determine how much is within the body. I am STILL emitting HIGH amounts of Gadolinium from my body post last MRIs by seven years tiem frame, a drug that is supposed to clear the body within 96 hours…
      European Medicines agency is going to be removing *four of the Gadolinium contrast agents in June, why not now and why not in the USA and entire world, is beyond me! IT infuriates me to no end that a drug can harm us and they are not yet held accountable! TO be continued…So please NO MORE MRIs with gadolinium contrast!


      * those being by name:
      Linear agents recommended for suspension by the PRAC are:
      Gadobenic acid, marketed as MultiHance by Bracco Diagnostics Inc.
      Gadodiamide, marketed as Omniscan by GE Healthcare
      Gadopentetic acid, marketed as Magnevist by Bayer HealthCare Pharmaceuticals
      Gadoversetamide, marketed as OptiMARK by Mallinckrodt Inc.

      There is testing info available at the Gadolinium toxicity site. Good luck with your medical issues. I am post ablation (2005) post double thryoidectomy (HRAS codeon 61) styloidectomy (eagle syndrome-elongated and calcified Left styloid bone) awaiting surgery to right styloid, but after removal of BOTH upper ribs for NTOS (Neurogenic thoracic outlet syndrome) yes it’s complicated…at present TSH 0.229 (Low) and some new nodules have shown up, seeing Endocrinologist this Tuesday

    • The short answer however is that the rT3 test is very expensive and the result does not change the treatment.

      My understanding of the rT3 mechanism is that it is not biologically available but does interfere with the negative feedback loop. The body recognizes rT3 the same as it does T3 and does not produce more thyroid hormone. This is apparently why people with this problem have normal TSH and T4 levels. It was explained to me that in some cases the rT3 needs to be flushed out to allow for the active T3 to be made available. This is all dependent on the mechanism of the underlying issue of course.