5 thyroid patterns that won’t show up on standard lab tests

July 8, 2010 in Thyroid Disorders | View Comments


diagnosis puzzleIn medicine, the key to choosing the best treatment is an accurate diagnosis. If the diagnosis isn’t correct, the treatment will be ineffective – or even cause harm.

Unfortunately misdiagnosis is common in the management of hypothyroidism. If you go to a doctor with hypothyroid symptoms, you’ll simply be given replacement hormones without any further inquiry into the cause of your condition.

Even worse, if you have hypothyroid symptoms but your lab tests are normal, you’ll be told you’re “fine”. If you insist you’re not, you might be sent home with an antidepressant, but no further clue about the cause of your symptoms.

The problem with this approach is that thyroid physiology is complex. The production, conversion and uptake of thyroid hormone in the body involves several steps. A malfunction in any of these steps can cause hypothyroid symptoms, but may not show up on standard lab tests. It’s incorrect and even negligent to assume that all cases of hypothyroidism share the same cause and require the same treatment. Yet that’s exactly what the standard of care for hypothyroidism delivers.

In this article I’ll present five patterns of thyroid dysfunction that won’t show up on standard lab tests. If you have one of these patterns, your thyroid isn’t functioning properly and you will have symptoms. But if you go to your conventional doctor, you’ll be told there’s nothing wrong with your thyroid.

A standard thyroid panel usually includes TSH and T4 only. The ranges for these markers vary from lab to lab, which is one of two main problems with standard lab ranges. The other problem is that lab ranges are not based on research that tells us what a healthy range might be, but on a bell curve of values obtained from people who come to the labs for testing.

Now, follow me on this. Who goes to labs to get tested? Sick people. If a lab creates its “normal” range based on test results from sick people, is that really a normal range? Does that tell us anything about what the range should be for health? (For more on the problems with standard lab ranges, watch this great presentation by Dr. Bryan Walsh)

The five thyroid patterns

  1. Hypothyroidism caused by pituitary dysfunction

This pattern is caused by elevated cortisol, which is in turn caused by active infection, blood sugar imbalances, chronic stress, pregnancy, hypoglycemia or insulin resistance. These stressors fatigue the pituitary gland at the base of the brain so that it can no longer signal the thyroid to release enough thyroid hormone. There may be nothing wrong with the thyroid gland itself. The pituitary isn’t sending it the right messages.

With this pattern, you’ll have hypothyroid symptoms and a TSH below the functional range (1.8 – 3.0) but within the standard range (0.5 – 5.0). The T4 will be low in the functional range (and possibly the lab range too).

  1. Under-conversion of T4 to T3

T4 is the inactive form of thyroid hormone. It must be converted to T3 before the body can use it. More than 90% of thyroid hormone produced is T4.

This common pattern is caused by inflammation and elevated cortisol levels. T4 to T3 conversion happens in cell membranes. Inflammatory cytokines damage cell membranes and impair the body’s ability to convert T4 to T3. High cortisol also suppresses the conversion of T4 to T3.

With this pattern you’ll have hypothyroid symptoms, but your TSH and T4 will be normal. If you have your T3 tested, which it rarely is in conventional settings, it will be low.

  1. Hypothyroidism caused by elevated TBG

Thyroid binding globulin (TBG) is the protein that transports thyroid hormone through the blood. When thyroid hormone is bound to TBG, it is inactive and unavailable to the tissues. When TBG levels are high, levels of unbound (free) thyroid hormone will be low, leading to hypothyroid symptoms.

With this pattern, TSH and T4 will be normal. If tested, T3 will be low, and T3 uptake and TBG will be high.

Elevated TBG is caused by high estrogen levels, which are often often associated with birth control pills or estrogen replacement (i.e. Premarin or estrogen creams). To treat this pattern, excess estrogen must be cleared from the body.

  1. Hypothyroidism caused by decreased TBG

This is the mirror image of the pattern above. When TBG levels are low, levels of free thyroid hormone will be high. You might think this would cause hyperthyroid symptoms. But too much free thyroid hormone in the bloodstream causes the cells to develop resistance to it. So, even though there’s more than enough thyroid hormone, the cells can’t use it and you’ll have hypothyroid – not hyperthyroid – symptoms.

With this pattern, TSH and T4 will be normal. If tested, T3 will be high, and T3 uptake and TBG will be low.

Decreased TBG is caused by high testosterone levels. In women, it is commonly associated with PCOS and insulin resistance. Reversing insulin resistance and restoring blood sugar balance is the key to treating this pattern.

  1. Thyroid resistance

In this pattern, both the thyroid and pituitary glands are functioning normally, but the hormones aren’t getting into the cells where they’re needed. This causes hypothyroid symptoms.

Note that all lab test markers will be normal in this pattern, because we don’t have a way to test the function of cellular receptors directly.

Thyroid resistance is usually caused by chronic stress and high cortisol levels. It can also be caused by high homocysteine and genetic factors.

Conclusion

The five patterns above are only a partial list. Several others also cause hypothyroid symptoms and don’t show up on standard lab tests. If you have hypothyroid symptoms, but your lab tests are normal, it’s likely you have one of them.

Not only do these patterns fail to show up on standard lab work, they don’t respond well to conventional thyroid hormone replacement. If your body can’t convert T4 to T3, or you have too much thyroid binding protein, or your cells are resistant, it doesn’t matter how much T4 you take; you won’t be able to use it.

Unfortunately, if you have one of these patterns and tell your doctor your medication isn’t working, all too often the doctor’s response is to simply increase the dose. When that doesn’t work, the doctor increases it yet again.

As I said at the beginning of this article, the key to a successful treatment is an accurate diagnosis. The reason the conventional approach fails is that it skips this step and gives the same treatment to everyone, regardless of the cause of their problem.

The good news is that, once the correct diagnosis is made, patients respond very well to treatment.

  • http://www.againstthegrainblog.com againstthegrain

    “These stressors fatigue the pituitary gland at the base of the brain so that it can no longer signal the thyroid to release enough TSH”

    I think you need to edit this misleading wording  - the thyroid doesn’t release TSH, the pituitary gland releases TSH to stimulate the thyroid to release thyroid hormones (not TSH).  I’m pretty sure you know this, but some might not.

  • Chris Kresser

    Thanks for catching that. I changed it to what it should have been in the first place (“thyroid hormone”, instead of TSH) I think my brain is melting down from too much studying. 4 weeks until the licensing exam, and I’m feeling it.

    I need a proofreader.

  • Julia

    Great post thanks Chris!  It’s great to know there are reasons thyroid tests come back ‘normal’ when they don’t feel normal at all.  Do you know much about using basal body temperature as a means of testing thyroid function?

  • Chris Kresser

    It’s not a reliable indicator. Too many different factors affect BBT for it to be conclusive.

  • sharon

    thank you for the article and best of luck on your test.  you’ll be awesome!

  • Elizabeth

    Wow, just wow. 55 years of Synthroid, several doctors including endocrinologists, and not one tested me for anything except TSH and free T4 and T3. I went through misery after misery, fought with those doctors, changed doctors. NOT ONE mentioned a possibility of any other problem with my endocrine system. I’m floored.

    This is depressing me since I don’t think I can find the kind of doctor I need in my area, At age 80, perhaps I will just have to do the best I can with my present situation. Outside of my hypothyroidism, and skin itching the dermatologists can’t find a reason for, I’m very healthy.

    Perhaps when I started Synthroid in 1955, there were no tests? I was just trying to get pregnant, at age 26, and my doctor tried the low dosage of Synthroid. It worked.

    Thank you, Chris, for your enlightenment. I’m sure that if I take this article to my endocrinologist, he will just pooh pooh it and tell me to stop reading junk science on the internet. :(

  • Angus

    This article displays  lack of understanding of basic thoiroid function. Taking the points above in order:
    1. T4 will be low in hypothyroidism secondary to pituitary dysfunction
    2. Control of TSH is dependant on feedback from T4 and T3 levels acting on the hypothalamus and pituitary. The action of T4 and T3 on inhibiting TSH production is proportional to peripheral activity (ie T3 has more peripheral activity  and more feedback (for a given concentration). Therefore if you are poor at converting T3 to T4 you will secrete excess TSH until the combined action of T4 and T3 is at a physiological level (T4 may be above ‘normal’ and T3 lower but overall activity will be unchanged.
    3. Assays which measured total thyroid hormone went out in the 1980′s. All assays used now measure free hormones therefore changes in TBG are irrelevent.
    4. Now I’m completely lost. Tempting to say you couldn’t make this stuff up but of course you have. High levels cause thyroid underactivity? Well obvoiusly thats why all those people with thyroid overactivity have symptoms of underactivity. Except they don’t they have symptoms of overactivity (sweats/palpitations/weight loss etc). Can you produce any evidence for this? Thought not.
    Also, for your information I expect the testosterone levels seen in female to male transexuals are rather (about 10 times) than the slight increases seen in PCOS.
    5. Untrue. Usually Thyroid hormone resistance (which is mainly inherited) affects the receptors in the pituitary and hypothalamus in a similar way to to those in the rest of the body. The end result is elevated TSH levels and T4/T3 but the peron with the condition has no symptoms.
    Sadly the symptoms seen with underactive thyroid are very non specific, really common, usually not caused by thyroid problems and often caused by complex factors with no simple cure. In trials where people with normal blood tests but symptoms of low thyroid are given thyroid hormone or placebo (inactive pill, e.g. sugar pill) (e.g. BMJ 2001;323:891-895) there was no benefit in giving thryoid hormone over placebo. Unnecessary thyroid hormone treatment carries a risk of side effects including osteoporosis and changes in heart rythm. There are good reasons why UK doctors who prescribe thyroid hormones to people without any evidence of deficiency are struck off and national guidelines are explicit in advising against (http://www.british-thyroid-association.org/news/Docs/hypothyroidism_statement.pdf).


  • http://www.againstthegrainblog.com againstthegrain

    FYi, it isn’t always necessary to go through a doc to get the tests you need (though it is great to have a good doc to help with test result interpretation – so I’m not knocking consulting with a good doctor).  In many, if not most cases, patients CAN order the tests themselves, without having to hurdle a gate-keeper doctor, pay unnecessarily for an office visit, or share the results (except in NYS where the legislature seems to think the residents are too feeble-minded to mind their own health).
    If you are willing to pay out-of-pocket instead of billing your insurance co, have a good PPO plan which will reimburse fees for any accredited lab, or if you already are paying out-of-pocket for lab tests, consider using a service that will allow patients to order their own tests.
    There are numerous labs that will take a lab order direct from patients, such as MyMedLab.com (no affiliation other than as a customer).  The test fees are often discounted, especially when “bundled” with other tests typically ordered for common conditions, and include the doctor’s order necessary to run the tests (except NYS, where this arrangement is specifically prohibited by law).  Test samples are collected at many convenient locations, including the widespread Lab Corp network.  Results are usually speedy and communicated directly to the patient, though can be also copied to a physician if desired.
    I couldn’t get my endo to run thyroid tests for thyroid antibodies (he said it wouldn’t make any difference in my treatment) so I ordered the test my self from MyMedlab.com and had the blood draw done at LabCorp.  I received an email the next day that my results were in (avail via secure log-in at the website).  The fee was very reasonable.
    I also have ordered my own tests at Enterolab.com to check for gluten sensitivity.

  • Sheila

    why have you not responded to what Angus wrote?

  • Chris Kresser

    I don’t have time to answer in the detail I’d like to right now because of my upcoming exam. So I’m going to wait until I do.

  • Lynn

    Something tells me Angus is from the BTA or the BTF, with his talk of good doctors being struck off. He seems obsessed with the TSH, which is a pituitary hormone for a start!

  • Chris Kresser

    Sorry it took so long to approve that comment, againstthegrain.  It got caught in my spam filter.

    I like directlabs.com for ordering labs w/o a prescription.

  • Jin

    Hi Chris, I noticed in this article about thyroid testing you didn’t mention Free T4 or Free T3.
    My MD has always ordered TSH, FT4, FT3, TPO & TgAb when checking my thyroid, stressing the importance of measuring the Free’s.
     
     

  • Chris Kresser

    T3 uptake gives a rough idea of free thyroid hormone status, is included on most standard lab panels, and is cheaper than running FT3 and FT4. But yes, if I am particularly concerned about the free hormones I’d probably run them too.

  • ben nguyen

    Low thyroid hormone supposedly can cause high cholesterol…
     
    Unfortunately, my doctor says all my thyroid numbers (t3, t4, etc) are normal.. so i’m on statins to keep my cholesterol on check (otherwise it shoots up to above 400!!))
     
    There’s a book by David Brownstein, that I’ve heard covers how to step by step diagnose thyroid issues!   In the meantime I’m minimizing my pufa intake, and increasing the number of antioxidants!

  • Elizabeth

    I don’t see the connection between thyroid hormones and cholesterol. I have hypothyroidism, have had for 55 years, and normal cholesterol. Ben, I’m really sorry you have to use statins. The only time I would recommend statins is in a case like yours becaue they can have deleterious effects.

  • Chris Kresser

    There is indeed a connection between hypothyroidism and high cholesterol. Thyroid hormone is needed to activate the LDL receptors. So when thyroid hormone is low, there will be a larger amount of LDL floating around in the bloodstream.

  • Stefan

    I think a lot or people are looking forward to a response to ANgus’s post.

  • Kathleen

    Can you please state which tests to order for a full thyroid evaluation  —name them in order in a way the lab will understand and/or I can take to my doctor.
    thanks for the great information.

  • Judi

    I am one of those people that is looking forward to your response to Angus’s comment.

  • Chris Kresser

    The problem is not what tests to order, but finding a doctor that knows how to do a proper thyroid evaluation. You can order the right tests, but if your doctor doesn’t know how to interpret them, it’s not much use. The standard tests I order for each patient are TSH, TT4, TT3 and T3 Uptake. If I suspect autoimmune involvement (almost always the case if TSH is elevated), then I’ll order thyroid antibodies as well.

  • Chris Kresser

    Sorry it has taken me so long to respond to this. As some of you know, I was preparing for the acupuncture licensing exam in early August, and then on vacation until last Sunday night.

    1. T4 will be low in hypothyroidism secondary to pituitary dysfunction

    That depends what you mean by low. It’s possible in this pattern for T4 to appear within the normal lab range, but below the functional range. Lab ranges are not based on scientific studies, but instead on bell curve analyses of patients who get tested in labs. Who gets tested in labs? Sick people. Therefore standard lab ranges represent what is “normal” for sick people, not what is normal for healthy people.

    What’s more, many people who have their TSH & T4 tested are taking supplemental hormones, which further skews the lab ranges.

    Finally, as much a we’d like to think that these feedback loops work in a textbook manner, they don’t. For example, I have a patient with confirmed Graves’ disease. According to the textbook, she should have low TSH (she does) and elevated T4 and/or T3 (which she never has). In fact, it’s not at all uncommon to have patients that don’t fit the expected patterns.

    2. Control of TSH is dependent on feedback from T4 and T3 levels acting on the hypothalamus and pituitary. The action of T4 and T3 on inhibiting TSH production is proportional to peripheral activity (ie T3 has more peripheral activity and more feedback (for a given concentration). Therefore if you are poor at converting T3 to T4 you will secrete excess TSH until the combined action of T4 and T3 is at a physiological level (T4 may be above ‘normal’ and T3 lower but overall activity will be unchanged.

    There is some controversy on this issue. But I can tell you that I’ve seen lab work on patients with normal TSH, normal T4 and low T3. If it were always true that low T3 would increase TSH, then such a result shouldn’t be possible. But as I mentioned above, patients very often don’t present with the textbook pattern.

    I’ve also seen and heard of patients improving when treated for T4 to T3 conversion problems even when their TSH is normal.

    3. Assays which measured total thyroid hormone went out in the 1980′s. All assays used now measure free hormones therefore changes in TBG are irrelevent.

    I don’t know what it’s like in the UK, but here in the US the standard measurement is total thyroid hormone (which includes free and protein bound). Few doctors order free T4 or free T3 routinely. Therefore TBG is not at all irrelevant. This is why T3 uptake is still included on standard thyroid lab panels.

    4. Now I’m completely lost. Tempting to say you couldn’t make this stuff up but of course you have. High levels cause thyroid underactivity? Well obviously thats why all those people with thyroid overactivity have symptoms of underactivity. Except they don’t they have symptoms of overactivity (sweats/palpitations/weight loss etc). Can you produce any evidence for this? Thought not.

    It is well-known that receptor site expression and sensitivity are both down-regulated in the presence of excess hormones – whether thyroid, insulin, leptin or other.

    It’s true that a large excess of thyroid hormone will produce hyperthyroid symptoms. But it’s a question of scale. To illustrate this, let’s look at a similar pattern that occurs with another hormone: insulin resistance. Chronic elevations of insulin cause insulin resistance. The cells are less sensitive to circulating insulin and hyperglycemia results. However, what happens if you give a hyperglycemic an insulin shot? They become hypoglycemic. Even though their cells are insulin resistant, they still have some receptor site activity, and the flood of insulin from the shot is enough to activate the receptors – whereas the smaller amounts of insulin produced from eating food is not.

    Thyroid hormone resistance with decreased TBG is similar to what I described above. The elevations in free thyroid hormone are enough to down-regulate receptor site activity, resulting in decreased proteonomic response. However, in hyperthyroidism, the level of circulating free hormones is more analogous to the levels of insulin after a shot. These much higher levels are still able to activate the receptors and increase proteonomic response.

    5. Untrue. Usually Thyroid hormone resistance (which is mainly inherited) affects the receptors in the pituitary and hypothalamus in a similar way to to those in the rest of the body. The end result is elevated TSH levels and T4/T3 but the person with the condition has no symptoms.

    Sadly the symptoms seen with under-active thyroid are very non specific, really common, usually not caused by thyroid problems and often caused by complex factors with no simple cure. In trials where people with normal blood tests but symptoms of low thyroid are given thyroid hormone or placebo (inactive pill, e.g. sugar pill) (e.g. BMJ 2001;323:891-895) there was no benefit in giving thyroid hormone over placebo.

    My answer to #4 above addresses this. Of course there would be no benefit to giving thyroid hormone to people with resistance. Their cells can’t use it. The factors causing resistance in the first place must be addressed for these people to improve.

    This is one reason why people on supplemental thyroid hormone continue to need larger and larger doses.

  • Carina

    “In trials where people with normal blood tests but symptoms of low thyroid are given thyroid hormone or placebo (inactive pill, e.g. sugar pill) (e.g. BMJ 2001;323:891-895) there was no benefit in giving thyroid hormone over placebo.”

    I´m curios how these trials can possibly work, since you have to raise your thyroid hormone until symptoms are relieved and the sufficient amount is so individual. For me it took 100 mcg of tyroxin to get any real benefits, but even that wasn´t enough. I did feel a little better on 50 mcg than on nothing but I was still sick as a dog. I would have probably been written off as one that didn´t respond better than placebo. How high a dose do test patients get in such studies? And do they raise the dose every 6-8 weeks as a normal thyroid patient would?

  • Chris Kresser

    Carina,

    The point of this article is that there are physiological mechanisms which depress thyroid function that won’t respond to standard thyroid hormone replacement.

    For example, if your cells are resistant to thyroid hormone, supplemental thyroid hormone will have a limited effect. If you underconvert T4 to T3, taking Levothyroxine or another T4 replacement won’t help much.

    The reason thyroid patients have to continually increase their dose is that these underlying mechanisms aren’t being addressed. It’s not “normal” to have to raise the dose every 6-8 weeks. It might be common, but it’s not normal.

  • lynn

    I assume Carina meant that when you first start treatment you increase the dose every 6-8 weeks until optimised. Not that you change the dose every six weeks for the rest of one’s life. This is very common when the above mechanisms are not addressed or a person is on T4 only though.

  • Carina

    Chris,
    I guess I digressed there from your article, but these questions always pop into my head when I hear of trials like the one mentioned.

    I really thought it was normal to raise the dose quite a bit. But even so, if some of the test persons had one of the underlying dysfunctions, then that would skew the results, so I would still say that there are problems with trials trying to determine whether or not patients with “normal” labs would benefit from thyroid meds.

  • Chris Kresser

    But that’s exactly my point, Carina: that “normal” thyroid labs don’t necessarily equate “normal” thyroid function. This is the argument I’m making in the article.
    These 5 mechanisms I listed here can suppress thyroid function, but they won’t necessarily show up on lab tests and they won’t necessarily respond to replacement. The value of those trials is that they confirm that replacement won’t work for patients when their underlying mechanisms haven’t been addressed.

  • lynn

    Hi Carina

    It is normal to raise the dose quite often when you first add thyroid hormone. You do this until you reach your sweet spot. Then, some need to increase slightly in winter and decrease a bit in summer. Otherwise, if you need to constantly tweak your dosage there is something wrong. Check out all the things Chris mentioned in his series as well as ferritin, B12, electrolyte and adrenals.

    Also, T3 or natural thyroid works better for most.

  • Carina

    Lynn,
    Yes, I meant raising the dose until optimised.

    Chris,
    I´m with you. I was just pondering the accuracy of such trials. I guess I should have directed my question to Angus who was the one mentioning it in his comment.

  • http://healingfolliculitis.blogspot.com Bill Mullan

    Hey Chris

    I am hoping you can help me. I have many of the thyroid symptoms, but all my levels check out:

    TSH 1.27, FT4 1.1 and FT3 3.7

    Negative or “normal” for antibodies. TSH was tested separately and I was on “the raw milk diet”for both the tests.

    Testosterone was 306 on the first test, on the second it was 438. I was not fasting during any of these tests which I now have read could screw up results.

    I have been gluten-free, Primal type diet, no cheats with any grains whatsoever, since December. Unless there was gluten in something I ate at a restaraunt, although I was very persistant about being “gluten intolerant.

    I have had folliculitis caused by gram negative organisms, usually Enterobacter Aerogenes for 3 years, it waxes and wanes. It’s not “horrible”, but it definitely has ruined my face.

    I have been on Tetracycline in 2003 for Acne. Then nothing till 2007, where since I have been Doxycycline twice, Amoxicillion, Erythromiycin, and Clarithyromycn. Never for more than a month at a time.

    Obviously my gut flora is screwed. I did the raw milk diet and am now taking Theralac and Ohhiras. The condition has improved and definitely improved when I let go of topical therapy (a huge waste).

    But now my thyroid symptoms are really showing up, and I can’t tell if my folliculitis is flaring from the very dry skin from thyroid, or if the Enterobacter is still going strong. I wanna say it’s both.

    I was VERY underweight for about a whole year (all of 2007, some of 2008)due to being an overzealous cross country athelete who could not recognize when my overly competitive attitude was doing me wrong. I restored my weight with a junk food-binge type diet quickly by 2008.

    Found Primal in 2009. Many health problems left. But now things are much much worse. Did Zero carb for a bit, Very low carb for a few months.

    Never had thyroid symptoms till now, but clearly I had them coming.

    I am guessing my pituatary, adrenals, and thyroid are just fed up with me.

    I have been overfeeding, at least 2500-3500 calories a day for about two months now. There have been days when I feel and look great. But then days where I feel horrible, my eyes get puffy and baggy, skin flaring.

    Really don’t know where to go. I really just want that fecal therapy done to correct my gut flora, and then address the rest of the issues. I am afraid to go on antibiotics again unless I can get fecal therapy right after. Folliculitis get’s worse after each antibiotic and I really don;t need any other immune issues.

    I am ruling out Hashimoto’s for now. Just because for years I ate gluten and never had any thyroid symptoms. I gained and lost weight like a normal person, slept alright, didn’t really display any food intolerance symptoms besides acne and ADD, some anxiety sometimes about sleep.

    Too long of a comment, I am sorry. Hopefully I can get some advice. I have a doctor at Whitaker Wellness.. but so far that is going no where.

  • Chris Kresser

    Bill,

    I wish there was an easy answer I could offer you. As you have no doubt gathered, thyroid physiology is complex and multi-factorial. From reading your story, I suspect (as you do) that it’s your HPA axis that’s driving your symptoms. This isn’t uncommon – I have several patients with normal thyroid labs, but still have weak thyroid function secondary to pituitary or adrenal dysfunction.

    There’s really no way to know more without doing a full work-up. If you’re interested in that, please visit my professional site to learn more about how I work with people and schedule a free, 15-minute phone consultation.

  • Lynn

    Chris

    What are the ranges for the FT4 and FT3 Chris? TSH is not a useful test really.

  • Lynn

    I meant to address that to Bill. :)

  • Chris Kresser

    Lynn: I disagree that TSH isn’t useful. I think it’s very useful. It tells us what hormone levels are feeding back on the pituitary, and whether the pituitary is functioning properly.

    Bill’s FT3 and FT4 levels are within both the functional and lab ranges.

  • Lynn

    I should have phrased that more clearly. I meant that that the FT4 and FT3 are more important than the TSH, and that just because his TSH is low does not mean he is euthyroid.

    Without ranges, it is hard to tell where Bill’s numbers are though. Ranges differ from lab to lab and they don’t all use the same units.

  • Chris Kresser

    Ranges don’t differ that greatly, in my experience, for FT3 & FT4. He’s at the high end for FT3, though he is towards the low end for FT4. It’s more likely he has thyroid receptor site resistance secondary to dysregulated cortisol rhythms. It’s perfectly possible for people to have normal thyroid labs and still have symptoms.

  • Lynn

    Well some labs use the range 2.0 – 4.4 for FT3 and other labs use the range 4.0-6.8 for example. People who are doing well (absence of thyroid symptoms) on their thyroid meds tend to have their FT3 at the very top or slightly over the range. This observation comes from years of interaction at patient groups. Apparently the ranges used to be higher, which explains this.

  • Chris Kresser

    But he’s not on thyroid meds, unless I missed something?

  • Lynn

    Nope, he isn’t, but the point of thyroid replacement is to mimic normal phsyiology. So, if thyroid patients do best at the top of the FT3 range; I would venture that healthy people should be there too.

    I also FIRMLY believe in fixing underlying causes low thyroid such as low adrenals, low iron/ferritin, low B12, gluten intolerance etc.

  • http://healingfolliculitis.blogspot.com Bill Mullan

    I forgot to add that at the moment (as of yesturday) I have started to supplement Betaine HCL, as I also have some symptoms of low stomach acid. Not sure if I will get any results from that.

    I have scheduled a phone consultation. Thank you Chris.

  • http://twitter.com/nkolin01 Nicole Kolinsky

    What about when labs indicate Hashimoto’s but I felt healthy with no hypo symptoms to report (I had a TSH of 10, FT4 of 1.0, and FT3 of 297, TPO >1000, ATA 1268)? I went off gluten for 5 months and now my TSH is 2.08 and all of a sudden I feel terrible — brain fog, fatigue, mild depression (FT4 of 1.2, TPO 447, and ATA 260). I started a dose of Armour Thryroid a week ago and am hoping this will help alleviate these unpleasant symptoms!

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