More BAD news if you are on T4-only like Synthroid??: It might cause Lung Cancer, says a study!


After worldwide patient experience has revealed that T4-only treatment results in a slew of continuing hypothyroid symptoms, now we have a study which implies that T4-only treatment could be raising your risk of LUNG CANCER.

This complete study came out just last Thursday, August 8, 2013, in the Reproductive Biology and Endocrinology journal and it’s certainly not good news, if true, on top of what thyroid patients already know has been a failure in so many ways.

The Italian authors said the correlation between lung cancer and T4-only treatment was “significant“!

In other words, says the study, as hypothyroid patients raise their T4-only levothyroxine medication to chase continuing symptoms of hypothyroidism, it can lead to medication-induced hyperthyroid state, which in turns leads to an overproduction of oxidative stress.  The latter oxidative stress is a known cause of cancer and other chronic diseases. But with T4-use, it’s specifically problematic for lung cancer, implies the study.

Oxidative stress can be defined as a that which results in “significant decrease in the effectiveness of your iinherent antioxidant defenses, such as glutathione” (Wikipedia). And there are two main consequences:  your body doesn’t detoxify itself well, nor does it repair any damage well because of free radicals.

The study states:

The prevalence of breast, colorectal, gastric and lung cancer in 18 Italian Regions during 2010 was correlated with the sales of LT4 in 2009. The cancer prevalence was analyzed in women aged 3084. This age range corresponds to more than 80% of the consumers of the drug and to about 99% of all malignant cancers. The correlation between sales of LT4 and cancers was determined with the technique of Density Ellipses. The age and smoking contribution for lung cancer was determined with the Sequential test.

It also adds:

Lung cancer was the only tumor found directly correlated with LT4 supplementation.

It’s particularly interesting to note that simply being hypothyroid results in increased oxidative stress, but the use of T4-only medications creates the same problem via a different route, explains the study. “LT4 can alter the oxidative balance in lungs and behave as a negative factor because of oxidative stress….” 

The authors conclude that “hypothyroidism might also be involved in the development of lung cancer”, but the study does send an alarming message about the correlation between T4 use and lung cancer, as well.

The website Green Med Info, which promotes natural and integrative modalities, goes further into the discussion about the problematic nature of treating hypothyroidism with T4-only, stating

One of the main drawbacks of administering T4 in isolation is the possibility that it will not convert adequately to T3, and will therefore ‘back up’ causing excessive T4 activity, i.e. hyperthyroidism. There is also the very real possibility that T4 will not only not properly interact with thyroxine cellular receptors, but will block out what remaining natural levothyroxine the thyroid is still producing (and whose conformational state is far more health-promoting), essentially acting as an endocrine disrupter at the very moment that it is acting as intended as a ‘TSH suppressor.’ This T4 blocking/endocrine-disrupting property of the synthetic form would also activate a negative feedback loop within the endocrine system, further suppressing remaining thyroid function, and resulting in the atrophy of the compromised thyroid, a iatrogenic ‘self-fulfilling prophecy’ if you will.

And they conclude: “There is also compelling research indicating that desiccated thyroid extract (Armour thyroid) results in superior clinical outcomes versus the synthetic hormone, especially as concerns improved body weight.” And of course, patients who have switched to natural desiccated thyroid (NDT) have reported FAR better results repeatedly! Brands are not limited to Armour. Other brands which patients like include Erfa, Acella (NP Thyroid), Naturethroid, Westhroid-P and more.

Message to those still using T4-only

Millions of hypothyroid patients have reported millions of prices in their own degree and kind thanks to their use of T4-only medications. Now we have a study that implies your risk of getting lung cancer is increased. What’s next?? It’s not a pretty picture, if the correlation turns out be accurate for some. Time to take a strong and open-minded look at what patients have learned.

ADDENDUM FROM JANIE: Please note that this study doesn’t say that every single T4 user is going to get lung cancer. My mother was on Synthroid her entire life, and though she had many miserable symptoms from it being a poor treatment for her, she never got lung cancer. It just seems to say that the researchers noted increased oxidative stress with T4 use, and they saw a correlation between that and lung cancer in some. Read the entire study information here and decide for yourself. 




Important notes: All the information on this website is copyrighted. STTM is an information-only site based on what many patients worldwide have reported in their treatment and wisdom over the years. This is not to be taken as personal medical advice, nor to replace a relationship with your doctor. By reading this information-only website, you take full responsibility for what you choose to do with this website's information or outcomes. See the Disclaimer and Terms of Use.

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61 Responses to “More BAD news if you are on T4-only like Synthroid??: It might cause Lung Cancer, says a study!”

  1. Christine says:

    Hi Janie-
    Quick question about this… I have been reading alot of articles about T4… my question is is it just from what they put in t4 medicine itself or is it the fact that you can’t get “optimal” on t4 only which then creates the issue of oxidative stress which can lead to the cancer? My mom is on synthroid and on generic cytomel both. Or is it better to be on compounded t4 and generic cytomel due to the cancer risk? Hopefully this makes sense! Thank you!!

    • Here’s what we’ve noticed: It’s very rare for anyone to get truly optimal by forcing themselves to live for conversion alone. They think they are, but they rarely are, even if they think they feel good on T4-only.

      And second, there are a lot of people who just aren’t great convertors of T4 to T3. They do convert, but not enough. That appeared to be me. T3 is what changes our lives, not T4.

      Third, there are too many life situations which can inhibit the conversion of T4 to T3. A LOT of them. Illnesses, stress, age, other medications, certain foods…and the list goes on.

      So, we have just observed and learned all these years that it’s just not a pretty picture for what seems like a majority to force the body to live for conversion alone. And common sense tells us we need some direct T3, as a healthy thyroid gives people in the first place.

      By the way, this article is based on speculation. I don’t think it proves that people on T4 will get lung cancer. It’s just presented as a possibility. But what is more obvious is that too many people on T4-only see symptoms of a poor treatment…of still having hypothyroidism. And that’s not good.

      • Christine Worke says:

        Thanks Janie!! My mom is on T3 as well. We both felt terrible on t4 only so I 100% agree with that! I just wanted to make sure it wasn’t like the synthroid itself. I myself have switched over to compounded t4 and then generic t3 just because it was “cleaner” but it also ends up being more expensive too. Thank you again!

  2. Brian says:

    My mom started taking a T4 and very quickly developed lung cancer…. The docs who prescribe this crap should go over the fact it is correlated to lung cancer, No if ands or buts.

  3. jj says:

    where is a good doctor is south south georgia or north florida…i have never tested positive for anti bodies in 5 years, i was diagnosed when i went menopausal after a tragic 2 years of stress and never felt like it was really hypothyoidism but deficiences in other hormones and vitamins bec i HAD NOT eaten well for 3 years b4 that and under alot of stress…..but now on 100 synthroid and have adrenal fatigue….but so hard to find a dr that really doesnt believe all the big hype and drug pushers

  4. ann says:

    I have being on thyroid 4 over 20 years I am on 200mg over the past 4 weeks I have pain in my lung so sore

  5. Pam says:

    Scary but good info to know. I was on Levo or Synthroid for many years, then compounded T4/T3 then Levo again and now on Armour Thyroid. I was diagnosed with pleurisy several years ago when I want to emergency room with severe chest pains. So it is very interesting to know this could be related to my thyroid medications. I had no idea. My new current endo loves Levo and prescribed hat to me at my first visit. . He reluctantly put me on 60 mg (30 mg 2/day) Armour Thyroid at my request at my 2nd visit but will not increase it after being on it a month, even though the 150 mg of compounded T4/T3 that I was on before with another doctor who moved, never gave me problems but was still not high enough in my opinion as I still had the hypo symptoms. He actually said more thyroid medicine for me would be like speed, because my test scores are “normal.” He did not care that my symptoms have not improved at 60 mg/day. He said prescribing me a higher dose might put me in the hospital. He is quite proud he is conventional, at his patient’s expense. So the search continues for a doctor who will treat me clinically for my symptoms and not blindly follow test scores. Very frustrating that I cannot find a doctor that is willing to work with me to adjust medications until I feel better. So tired of feeling crappy all the time.

  6. Jan says:

    Ok now I have another worry to fuel my health anxiety. I totally freak out on T3 meds. have tried T3 on its own – extremely low dose (got heart palpitations and tachycardia – went away as soon as I stopped the T3), then tried NDT three quarter grain twice daily (was out of my mind- palps were horrendous). Now I am on thyroxine again 50mg much better but still a little anxiety and am suspecting I may have to raise my dose but now I guess I can just sit back and wait to get lung cancer, another worry to aid my anxiety.

  7. Melissa says:

    I was on T4 only for 20 years, and seriously knew I was slowly dying on it. I did a lot of research and found a group on FB who literally saved my life. Read the book Stop the Thyroid Madness and search for a thyroid group – amazing how much some of these people know. Natural thyroid is turning my life around (and in some cases you don’t need a prescription to order it online)

    • Joy bridges says:

      What websites do I go on to order it without a prescription.

      • Joy, do an internet search for bovine thyroid or bovine glandulars. They aren’t always perfect, as they sometimes push RT3 high based on when the cow was slaughtered, it appears. But are always worth a try if you can’t get your doctor to prescribe.

  8. Linda says:

    My VA (Veterans Administration) doctors, including the endochronologists, will not even discuss switching me to NDT even though I used it successfully for one year. It was a wonderful year. Then I moved and my new doctor would not continue with NDT . I considered going online to purchase it, but I was afraid of the unknown. I want my doctor to understand how different my entire life was without synthroid.

    I am going to explore all the recommendations on this forum to find the right solution for me. By the way, I found out that when I stopped eating gluten, some of the worst symptoms disappeared. I am going to read the article mentioned above about how gluten affects the thyroid. I will take all this information to my doctor along with my old prescription for NDT.

    Other serious conditions that I have had include Chronic Pancreatitis and Glocoma and Pneumonia (3 times).

  9. Donna B says:

    I’ve been on NDT for 2 years. Suddenly, my holistic Dr. retired so I turned to an endocrinologist. He immediately reduced my NDT and eventually added Levothyroxine. I am 54 and post menopausal(haven’t had a period in 2 years!) and a month after starting the Levothyroxine I got a period! The Endo says that means the Levothyroxine is working and has returned my body to it’s natural state because my periods have returned?! What, at 54 the return of my period is normal??? Really-he said that I never really went through menopause it was just the thyroid imbalance. The pharmacist says it is totally possible for the levothyroxine to induce my period even being menopausal. Ugh! Has anyone had anything like that as a result of T4?

    • One grain of NDT is approx. 38 mcg of T4 and 9 mcg of T3. So it may be that he added enough T4 to more-than-compensate for what he lowered, making it all like a “raise” in total thyroid meds. But do know that the direction he went with you is backwards, say a lot of patients. You might have gotten better results just from raising your NDT–the latter which gives you all five hormones that a healthy thyroid makes.

  10. jeff says:

    Dont take t4 poison read please

  11. KOral says:

    Synthetic Thyroid pills like Synthroid or Levothyroxine are NOT a must. Get diseccated thyroid which is natural, 100% of people who are on that see improvements. A great resource is Dr David Braunstein’s book : Overcoming Thyroid disorders.
    I’ve been for 5 yeard on synthetic with condition worsening. Now , for the last year I am on natural with every MD trying to get me off them… But I must say that I feel much better and in fact the amount needed is improving.

  12. Nicole says:

    Wow… funny, as soon as I started taking levothyroxine I got pneumonia! 🙁 what is ndt??? I need to do something about this! Lung cancer runs in my family!! Here I am eating healthy organic foods, throwing away my non stick pans… trying to make the right decisions… and I’m pretty much poisoning my self! So does this effect a baby when taking it?? I took it my entire pregnancy!!

  13. Jeff says:

    I have been taking throid replacement for about 20 years. For most of that time I have been on the generic version. I few years ago I started having symtoms of hyper thyroid after getting a new monthly supply. A few times I have taken them back to the pharmacy and told them about my problems and asked if they could be a bad dose and asked them to replace the pills with a different lot. They have and usually it solved my issues. My issues were insomnia, irritability, and heart palputations. For the last few years I have been on synthroid brand because of my sensibility to the generic variations, with none of these side effects. This last month I have had the same side effects with the synthroid. Insomnia was the worst. I got a new monthly supply a week ago and all of the side effects went away and things are back to normal. I can tell that my pharmacist and Doctor think I am crazy when I suggest that the dose is wrong with a particular monthly supply and want a new supply. Has anyone ever heard of this problem? Am I just overly sensitive to slight variations when these pills are manufactured?

    • Hi Jeff. Because patients have found Synthroid to be a lousy treatment for hypothyroidism, many report they end up with adrenal problems because of it, which can cause the symptoms you are describing. Go here:

    • Laura says:

      Back when I was on Synthroid (now I am on Armour Thyroid), I had a bad batch. Within three doses, I was extremely hyperthyroid (could not even close my eyes, was doing pushups in my living room at 2:00 am and could not stop, racing heart). It was really scary. I reported it to the doctor and the FDA. The doctor thought I was nuts and I never heard anything from the FDA.

  14. SABRINA says:


  15. Laura says:

    I was just recently told that I have a 4 mm on my left lobe, I have never smoked. Doctor said come back in a year, I predicated that. I decided to see if their is a connect between Levothyroxine and Lung Cancer, and found these articles online. I have severe Chronic Pain through out entire body.

  16. Rose says:

    This is frightening. My doc has been slowly increasing my dosage of Synthroid. Last winter, I developed pneumonia and pleurisy.

  17. Andrea says:

    Jamie, I have been noticing a cough here where I can NOT seem to figure out where it is coming from. I have never smoked a day in my life.I am on that gel form of synthroid. The cough drives me up the wall and mom and I have exhausted anything else it could be.

  18. Jim says:

    That “study” just compared the number of cases of lung cancer in an area of Italy to the amount of levothyroxine sold in that area. It did not address whether the lung cancer patients were taking levothyroxine. That is about as dumb as saying that toothpaste use causes cervical cancer, because in countries where toothpaste is commonly used, there are more diagnoses of cervical cancer. Just to be clear, toothpaste use is higher in developed countries, where they also end of finding more cervical cancer because they are able to find it. By the way, I have been eating carrots for 50 years, and I now have a torn meniscus in my left knee. Those darned carrots!

    • Kevin says:

      Uhyou are aware that Density Elipses is a legitimate and common analytical tool used in pharmaceutical studies? Which is the method they claimed they used to determine correlation. They didn’t stop there though. Four cancers correlated with the T4 only med use, but the study found only lung cancer was directly associated with the meds. They went on to explain why. The statistical analysis was only the starting point. Like a criminal investigation – four guys were in the area at the time of the incident, so all four are persons of interest but ultimately only one was found to be directly involved. The starting point for data in the case is the assessment of correlating factors.

  19. Totto says:

    But we don´t know if NDT also causes lung cancer, do we? Or if combination therapy does.

    • Janie says:

      Until we get more info, I think all we can do is intelligently speculate. The article was more about potential oxidative stress (and hypothyroidism) causing the connection between lung cancer and T4 use. So it’s what we might be doing to cause oxidative stress, which I’m not sure NDT does, and which T4 use could definitely do, since it leaves so many patients with continued hypothyroidism. Or, I can see it could be about the way one doses exogenously. See the next STTM blog post about oxidation.

  20. Sturgess says:

    I’ve been taking Levothorxine since my total thyroidectomy in 2007. Took a couple of years to find the right dose, but since then I really feel great. So while your article is certainly food for thought, I’m not inclined to fix something that’s not broken.

  21. David says:

    I have been taking levothyroxine for over 30 years and I have lung cancer!

  22. ekw0357 says:

    Synthroid & Levo = Poison

  23. Yvonne says:

    I hope that each reader who’s on levothyroxine prints the linked research document and shows it to his or her endocrinologist! Doctors need to know about this research as further justification for trying NDT in those hypothyroid patients who don’t do well on levothyroxine. Janie, thank you for sharing this with your readers!

  24. Valerie says:

    I recently had my right lung removed due to lung cancer, and never was a smoker who has taken Synthroid for about 20 years. I am convinced there is a co-relation between my thyroid/auto immune issues and the cancer. Unfortunately, I do not transition well to ANY T3 products so far. It sets off my auto-immune reaction. But, I am working with a physician to get where i need to be so I can try an NDT product again.
    AMEN to being aware of everything we can to help ourselves.

    • Diane says:

      God bless you and thanks for sharing. I’ve been taking T 4 for 8 years & suffered tremendously I’ve had RAI, & had Graves disease please hold on to your thyroids if feasibly possible. A great healer is Dr Osansky I only wish I found him before I ablated my thyroid, but I was too desperate too sick at the time to think clearly and investigate other options. These Ivy League Drs ought be ashamed of themselves, I live in Brooklyn NY & you’d think you’d get the best of the best treatment but most Drs – endocrinologists are behind the times. I just tried Armour thanks to us the people’s blogs and thank you Janie I’ve read a lot online & you are the best by far patient advocate, better than another particular well-known one. I just bought your book & it’s a must read, God bless us and We must educate ourselves as much as possible or most Drs will leave us with half lives & be satisfied

  25. Jackie says:

    Gail, to be armed with knowledge, empowers you to be your own health advocate. Dr.’s do not know everything. It’s just that simple. They are people just like we are. If you don’t feel at this point in time you have a choice about taking T4, then at least armed with this knowledge, you have the ability to increase your own self care. To Detox on a daily basis, look into Green Smoothies. We can’t simply rely on modern medicine for our health. We must be aware and do everything we can to help ourselves!!!

  26. Renee says:

    Anytime new truths are brought out into the open, that has to be welcomed, even if it is kind of scary at the time. We need to be aware of these things and make sure our doctors are aware also.

  27. Gail says:

    Why are you frightening people who have no choice but to take the T4 they are given?????????

    • Janie says:

      Hi Gail. This is just about risk. It doesn’t guarantee you’ll get lung cancer. But I would explore NDT with your doc, or at the least look at adding T3 to the T4. If you have ever had issues with either, you could be here:

    • SG says:

      There is ALWAYS a choice..Look into how gluten effects thyroid function! And people should be scared…Ignorance is certainly NOT bliss when it comes to stuff like this!! It’s stupid to just ignore!!

      • Angela says:

        I agree very much with Gail. My doctor won’t even change my generic to name-brand and I DON’T have a choice. I don’t have health insurance and am only lucky enough to get treated through a payment program at one of our hospitals here. But I can’t go anywhere else, because they don’t offer programs like this one hospital does.

        You can inform people in an unbiased manner in a less frightening way. People SHOULDN’T be scared unless they have a reason to be. Meaning, there are LOTS of people who have been treated successfully with generic or T-4 only medication, but you likely won’t hear about them online because they are out there living their lives. The people who are online are here because they are searching for answers.

        So you could possibly be fine with your T-4 only treatment, but this article and the way it’s written would have you scared out of your wits that you’re harming yourself, for no good reason except that it didn’t work for a few others.

        It makes no sense. Take everything online with a grain of salt. Everyone is different and not everyone “should” be scared. Your excitement comes off as fanatical nonsense.

        • Janie says:

          Hi Angela. Patients really do have a lot of choices. I know of several who are choosing to use ThyroGold, for example, and work with a good doc. But also know that STTM is about patient experiences, not fanaticism. Hope T4 works out better for you than it has for so many others. 🙁

        • Jan says:

          Well Gail and Angela

          it is now 9/18/2014

          on 9/12/2014
          I was diagnosed with both thyroid and lung cancer. oh the thrill for me. but I have been struggling for 3.5 years to find the answer to why out of no where would I loose 80 lbs, no diet change, no change other then a few months before my daughter was married. I’ve have a gland in my neck my whole life that I can remember kinda big…. about the time I lost the weight it became very big and developed a pulse, I was told I’m nuts not in so many words…… now Im going to turn this around on the very health care facilities that said this. because I was basically ignored, I am not going to start my fight with a 12mm cancerous lump (node) and 6 or more nodes3-6mm in my lungs, yep both lungs lucky me I get the draw the short life span straw. So if you too want to feel scared because you were smart enough to stumble across this page before it was too late. Count your lucky stars…. because the outcome is not that good for me.

        • Kevin says:

          Totally disagree with you. Warning people of nasty negative effects of toxic medications is a beautiful blessing. My mother is having serious complications from this garbage, and I’d prefer she lives many more years and without the vicious side effects of this crap. There are natural alternatives which do not disrupt your system like this. How on earth is data on the dangers of a product “scaring people”? Is warning people who want to swim there are sharks in the reef “scaring people”? Go ahead, swim then. I’m personally very thankful for this article.

    • Resa says:

      Gail and Angela-There is always a choice. The one of the post below says…print this out and take it to the dr that is T4 only frenzy. Or find a new dr. Or order Thyroid-Gold. There is always a way. I don’t have insurance either and found a way. I searched and it was tough but found a dr that takes cash and gives a discount for low income. He’s amazing. And prescribes NDT and doesn’t let you suffer on T4 only. There is always a way. Just got to fight for it.

    • Sheryl says:

      My mother who is 92 and myself have been on a natural thyroid medication called Amour Thyroid. It is made from a pigs stomach. My mom has been taking it for 15 years and I have been on it for 5. We have very good results in our tests. The doctors of course keep telling us that its not available when we are up for renewal but I always say yes it is. Please just write the script and send it to my pharmacy. A couple years back when the US couldn’t order it I did have to order it from Canada but was a simple task. But no issues getting it ever since. Do some research– the less synthetic stuff we put in our bodies the better.

    • Ione says:

      There is an alternative to Synthroid. Armour is on the market and Wellness Resources has a product called thyroid helper when used in combination with iodine ( which is very deficient in people ) is amazing .

      • There are a few problems with this. One, it contains guggul which could mimic the effect of estrogen–the last thing some women need. Second, not everyone has low iodine, even if some do. Third, even if one’s iodine levels are low, iodine has frequently not been enough to treat hypothyroidism for many, even if for a very small minority, it has been enough. And finally, it is only a nutritional supplement, and a lot of patients need thyroid hormones to feel better, not just the supplements of ashwagandha, guggul, manganese and tyrosine. Granted, these facts don’t take away that some feel better on it! But for others, it can have problems, nor is it all they need. Most do well on natural desiccated thyroid.

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