Thyroid Hormone Deficiency - An Overview

Published: October 3, 2012

Parts used with permission from the book From Fatigued to Fantastic! By Jacob Teitelbaum M.D. (Penguin/Avery, Oct 2007)

Underactive thyroid function is becoming alarmingly common—and is horribly under-diagnosed. The good news is that once it is diagnosed, it can be very easy to address, and therapy can save your life in addition to making life worth living!

The thyroid gland, located in the neck area, is the body's gas pedal. It regulates the body's metabolic speed. If the thyroid gland produces insufficient amounts of thyroid hormones, the metabolism decreases and the person gains weight. Other symptoms of hypothyroidism include intolerance to cold, fatigue, achiness, confusion, and constipation.

Unfortunately, most physicians are not up to date with the research that shows that TSH (the main test used to check your thyroid) is VERY unreliable—missing MOST of the people who need thyroid. Even the "more reliable" free T4 test will only be considered abnormal if you are in the lowest 2% of the population (i.e., have thyroid failure).

The normal range for most labs are based on statistical norms (called "2 standard deviations"). This means that out of every 100 people, those with the 2 highest and lowest scores are considered abnormal and everyone else is defined as normal. Unfortunately, our testing system does not take biological individuality into account. To translate how poorly this "2%" system works, consider this. If we applied it to getting you a pair of shoes, any size between a 4 and 13 would be "medically normal." If a man got a size 5 shoe or a woman a size 12, the doctor would say the shoe size they were each given is "normal" and there is nothing wrong with it!

I believe that most people with CFS, Fibromyalgia, severe unexplained fatigue or pain, or perhaps even unexplained severe weight gain deserve a therapeutic trial of prescription Armour or compounded thyroid. If your doctor won't prescribe it, find a Holistic Physician.

Other useful tools include:

  1. If you can't get prescription thyroid, try natural support with an herbal supplement that supports natural thyroid function, a mix of thyroid glandular plus nutritional and herbal support, which can be very helpful.
  2. For my favorite (and free) thyroid newsletter, sign up at Mary Shomon's website. You'll be glad you did!

Ready to become a thyroid expert? Let's go!

The Thyroid Gland

The thyroid gland, located in the neck area, is the body's gas pedal. It regulates the body's metabolic speed. If the thyroid gland produces insufficient amounts of thyroid hormones, the metabolism decreases and the person gains weight. Other symptoms of hypothyroidism include intolerance to cold, fatigue, achiness, confusion and constipation (though diarrhea from bowel infections is common in CFS/FMS).

The thyroid makes two primary hormones. They are:

  • Thyroxin (T4). T4 is the storage form of thyroid hormone. The body uses it to make triiodothyronine (T3), the active form of thyroid hormone. Most synthetic thyroid medications, such as Synthroid and Levothroid, are pure T4. These synthetics are fine if your body has the ability to properly turn them into T3. Unfortunately, many people with CFS/FMS find that their bodies do not have this ability.
  • Triiodothyronine (T3). T3 is the active form of thyroid hormone. Although in some life-threatening illnesses the body appropriately makes less T3, research suggests that when CFS/FMS occurs, the body may not be able to adequately turn T4 into T3, or it may need much higher levels of T3.

The Problem with Thyroid Tests

Many years ago, while I was in medical school, physicians were taught to diagnose hypothyroidism, or low thyroid function, by using the newly discovered method of measuring the metabolic rate while the patient ran on a treadmill. Doctors thought that this was a wonderful new test and that they finally had a way to identify patients with underactive thyroids. We congratulated ourselves on being so clever. But then a new test came out. The new test measured protein-bound iodide (PBI). When doctors began using the PBI test, we realized, "Oh, we missed diagnosing so many people with a low thyroid, but this new test will now pick up everybody who has a problem." We patted ourselves on the back and told all our newly discovered thyroid patients that it turned out that they were not crazy—they just had a low thyroid. Doctors were comfortable that we could now determine with certainty when someone had a thyroid problem.

Then the T4-level thyroid test was developed and we said, "Oh, that silly old PBI test. It missed so many people with a low thyroid, but this new test will find everyone." Then the T7 test, which adjusts for protein binding of thyroid hormone, came out, and then the thyroid-stimulating hormone (TSH) test. Modern medicine is now beyond the fifth generation of TSH tests, and this is the only test that many doctors use to monitor thyroid function. With each new test, doctors realize they missed many people with underactive thyroid function. In 2002, the American Academy of Clinical Endocrinologists noted that anybody with a TSH under 3 should be given therapy for hypothyroidism, and that 13 million Americans had an underactive thyroid that was not being addressed because labs were being misinterpreted. Despite this, most labs still have a normal range for TSH that goes up to 5.5. To make matters more difficult, if the thyroid is underactive because the hypothalamus is suppressed, the TSH test, which depends on normal hypothalamic function to be at all reliable, may appear to be normal, or even suggest an overactive thyroid. In fact, when lecturing at a fibromyalgia conference in Italy, I spoke with Professor Gunther Neeck—the world's foremost expert on hypothalamic-thyroid axis dysfunction in fibromyalgia.8 I asked him a simple question "is the TSH test reliable in fibromyalgia?" He gave a very simple answer, which was "absolutely not!" Fortunately some doctors are finally starting to catch on.

In two studies done by Dr. G.R. Skinner and his associates in the United Kingdom, patients who were thought to have hypothyroidism (an under-active thyroid) because of their symptoms had their blood levels of thyroid hormone checked. The vast majority of them had technically normal thyroid blood tests. This data was published in the British Medical Journal.68 He then did another study in which the patients with normal blood tests who had symptoms of an underactive thyroid—those who your doctor would likely say had a normal thyroid and would not need therapy—were prescribed thyroid hormone. A remarkable thing happened when this was done (well, maybe we're not surprised!). The large majority of patients, despite being considered to have a normal thyroid, had their symptoms improve upon taking thyroid hormone (Synthroid), at an average dosage of 100 to 120 micrograms a day.69

These two studies, plus another one showing that thyroid blood tests are only low in about 3 percent of patients whose doctors sent blood tests in, confirm what we have been saying all along.70 Our current thyroid testing will miss most patients with an underactive thyroid. Once again, doctors of decades ago were on target when they knew that one has to prescribe based on the patient and not the blood test. Most blood tests cannot accurately measure T3 thyroid deficiency because readings measure only the level of T3 in the blood, and it's the level inside your cells which is important. Nonetheless, it may still be worthwhile to check total or free T3 levels if you and your doctor suspect T3 deficiency. Testing should occur before beginning T3 therapy, as the tests become unreliable once you begin taking hormones that contain T3.

Addressing an Underactive Thyroid

We are constantly learning powerful new tricks for addressing hypothyroidism and there are many reasonable therapy approaches. Our protocol information checklist (see below at the end of the article) gives the "nuts and bolts" of some approaches.

What therapy will work best often depends on what is causing your thyroid levels to be inadequate. Common causes of underactive thyroid hormone in CFS/fibromyalgia include:

  1. Hypothalamic dysfunction. Your thyroid gland may be fine but it is not getting adequate stimulation from the hypothalamus and is basically "asleep." In this situation, simply taking a mix of T4 and T3 (see below) at the dose that feels best may be adequate. As the CFS resolves and hypothalamic function recovers, you may often be able to wean off the thyroid hormone.
  2. Hashimoto's Thyroiditis. In this autoimmune process your body's immune system attacks and damages the thyroid. This can be diagnosed by a blood test called an "anti-TPO antibody." If the anti-TPO antibody is elevated, you likely have Hashimoto's Thyroiditis and may need to take thyroid supplementation for the rest of your life.
  3. Inadequate conversion of the T4 thyroid hormone to active T3. In this situation, which is very common in fibromyalgia, patients often respond best to therapy with pure T3 hormone. Blood tests are normal despite needing 9-27 mcg a day of T3 thyroid hormone (present in 1-3 grains of Armour thyroid).
  4. Receptor resistance. In this situation your body is making adequate amounts of thyroid hormone but the areas that they stimulate are very slow to recognize the thyroid hormones' presence. Because of this, it takes a very high level of pure T3 hormone to get a normal response. This problem often resolves over one to two years on the high-dose T3 therapy as the body heals from fibromyalgia and/or chronic fatigue syndrome.

Given the multiple causes of thyroid insufficiency in CFS and fibromyalgia, let's discuss how to best address these problems.

Thyroid Hormone

Most doctors prescribe T4 (Synthroid) to address an underactive thyroid. T4, though, is fairly inactive until the body converts it into T3, or activated thyroid hormone. If the problem is only with the thyroid gland itself, prescribing Synthroid will work just fine. However, during periods when the body wants to conserve energy (for example, during times of infection or with CFS/FMS), the body slows down its metabolism. It does this by decreasing the production of active T3 from T4, which is turned into inactive "reverse T3" instead. In some cases, the body may get "stuck," and becomes unable to make adequate T3. Because of this problem, many physicians prefer to use compounded or Armour Thyroid, which contains a mix of T4 and T3.

If you suffer from chronic fatigue and have achy muscles and joints, heavy periods, constipation, easy weight gain, cold intolerance, dry skin, thin hair, a change in your ankle reflexes called a delayed relaxation of the deep tendon reflex (DTR), or a body temperature that tends to be on the low side of normal, you should consider asking your doctor to prescribe a low dose of Armour thyroid hormone. As long as you do not have underlying heart disease and you follow up with a blood test to make sure that your Free T4 thyroid levels are in a safe range (going above the upper limit of normal may aggravate osteoporosis, a problem already common in CFS/FMS) a trial of low-dose thyroid hormone therapy is usually quite safe and may be dramatically beneficial.

I prefer to start with a trial of compounded T3 plus T4 or with Armour Thyroid, in which both T3 and T4 are already present. I begin with 1/4 grain (15 milligrams) a day and increase it to 1/2 grain (30 milligrams) a day in 3-7 days. Then, I increase it by .5-1 grain each 1 to six weeks until the patient finds a dose that feels best. If this therapy does not bring about relief, a trial of Synthroid, which only contains T4 may help. One hundred micrograms (0.1 milligrams) of Synthroid "equals" ¾-1 grain of Armour Thyroid. Often, one hormone therapy works when the other does not. Adjust the dose as above. You will know if the therapy is working within two to six weeks on a given dose.

If you are shaky, hyper, or have a racing heart (for example, a pulse over 90 beats per minute), lower the dose. In addition, try taking the full dose of thyroid in the morning on an empty stomach or half the dose twice a day to see which feels best. Do not take thyroid hormone within several hours of taking iron or calcium supplements, or you won't absorb the thyroid.70

Once you have found a dose that feels best or once the 2 and 3 grain levels are reached, your doctor should check the free T4 blood levels. The first test should be administered about one month after you've reached the optimum level described above and then once every 6-12 months. You may need to slowly adjust the thyroid supplementation so that you remain within normal range for blood Free T4 thyroid hormone levels.71 Do not allow your doctor to check a TSH test. It will be low (because of the hypothalamic dysfunction) and your doctor will incorrectly think you're on too much thyroid—even if your blood T4 hormone levels are low normal. This will make you and your doctor crazy! Although many patients can stop taking thyroid hormone after twelve to twenty-four months, you can stay on Armour Thyroid or Synthroid for as long as it is needed.

Another approach, used by John Lowe, D.C., a researcher in Boulder Colorado, is to use pure T3 hormone (Cytomel). He feels that FMS patients have "thyroid resistance"—that is, it takes a much higher level of thyroid to obtain the normal effect. Even though the body may only make about 25 to 30 micrograms of T3 a day, his studies found it took an average of 120 mcg a day to make his FMS patients feel healthy.72,73 We have found this approach to be helpful in many patients.

All prescription thyroid therapies must be prescribed and monitored by a physician. Holistic physicians are more likely to be familiar with and open to trying these new therapy approaches. Unfortunately, many doctors are incorrectly trained to stop increasing the dosage of thyroid hormone once an individual's thyroid tests are in the "normal" range—even if the dose is inadequate for that person. Do NOT let your doctor use the TSH test to monitor therapy once the TSH drops below 2—it is TOTALLY UNRELIABLE. Ask the doctor to only check the Free T4 level, and to allow you to adjust your thyroid dose as feels best as long as the Free T4 test stays in the normal range for safety.

Synthetic T4 (Synthroid) and pure T3 (Cytomel) is available at any pharmacy. Sustained-release T3, which works better for many patients, can be obtained from compounding pharmacies. When you settle on an optimal dose, the compounding pharmacy can then make a single capsule of that dosage to be taken one or two times a day. This is less expensive because the cost tends to be based more on the number of capsules than the actual amount of T3 in them.

Potential Side Effects

If someone has blockages in the arteries that feed the heart and is on the verge of a heart attack, taking thyroid hormone can trigger a heart attack or angina, just like exercise could. Thyroid therapy can trigger heart palpitations as well. These are often benign, but if chest pain or increasing palpitations occur, stop the thyroid supplementation and call your doctor and/or go to the Emergency room at once. Because of this concern, I sometimes recommend that patients at significant risks of angina with several risk factors—people who smoke, have high blood pressure, are over forty-five years old, have cholesterol levels over 260, or a family history of heart attacks in individuals under sixty-five years old-have an exercise treadmill test done before therapy, even if they can't complete the test.

To put the risk in perspective, in the many thousands of my patients on thyroid supplements, none experienced heart attacks or other major health issues from taking it. In the long run, I suspect thyroid therapy is much more likely to decrease one's risk of heart disease by lowering cholesterol.

The other main concern is that excess thyroid hormone can cause osteoporosis. In my research, I have seen no studies showing any increase in osteoporosis in premenopausal women, or even in post-menopausal women if they are on estrogen, if one keeps the T3 and T4 thyroid blood levels in the normal range. As noted earlier, TSH is simply not a reliable monitor of thyroid levels in CFS/FMS because of hypothalamic dysfunction. We don't know for sure if keeping the T3 level above normal in FMS patients with thyroid resistance worsens the osteoporosis already commonly seen in CFS/FMS, but this has not been a problem in Doctor Lowe's experience with thousands of patients. If you need to keep the T3 or T4 above the upper limit of normal, you should have a DEXA (osteoporosis) scan every 6-24 months. If this scan shows osteoporosis, lower the thyroid dose. If this is not possible, consider other osteoporosis prevention measures we discuss in our Osteoporosis overview.

Over-the-Counter Alternatives

If you are unable to find a physician who will write for prescription thyroid hormone, there are other alternatives. For many people, natural thyroid glandular supplements can be very are helpful. Thyroid hormone is made of Tyrosine plus iodine, and blue flag root is a thyroid stimulant. The thyroid glandular supplies the raw materials needed to optimize thyroid function.

Related Information:

"Risks of Missing Hypothyroidism"

Hormonal Therapies

This section is from our therapy protocol. It discusses how to use thyroid hormone.

Thyroid supplementation—several studies show that thyroid therapies can be very helpful in CFIDS/FMS—even if your blood tests are normal. This therapy is, however, very controversial—even though it's usually very safe. All therapies (even aspirin) can cause problems in some people though. The main risks of thyroid therapy are:

  1. Triggering caffeine-like anxiety or palpitations. If this happens cut back the dose and increase by ½ to 1 tablet each 6 to 8 weeks (as is comfortable) or slower. Sometimes taking vitamin B1 (thiamine) 500 mg 1-3x day a day will also help after about a week. If you have severe, persistent racing heart, call your family doctor and/or go to the emergency room.
  2. Like exercise (i.e., climbing steps), if one is on the edge of having a heart attack or severe 'racing heart' (atrial fibrillation), thyroid hormone can trigger it. In the long run though, I suspect thyroid may decrease the risk of heart disease. If you have chest pain, go to the emergency room and/or call your family doctor. It will likely be chest muscle pain (not dangerous) but better safe than sorry. To put it in perspective, I've never seen this happen despite working with many hundreds of patients with thyroid problems. Increasing your thyroid dose to levels above the upper limit of the normal range may accelerate Osteoporosis (which is already common in CFIDS/FMS). Because of this, you need to check your thyroid (Free T4—not TSH) levels after 4 to 8 weeks on your optimum dose of thyroid hormone. All this having been said, we find therapies with thyroid hormone to be safer than Aspirin and Motrin. If you have risk factors or Angina, do an exercise stress test to make sure your heart is healthy before beginning thyroid therapy. These risk factors include: 1. Diabetes, 2. Elevated cholesterol, 3. Hypertension, 4. Smoking, 5. Personal or family history of Angina, 6. Gout, 7. Age over 50 years old.

There are several forms of thyroid hormone, and one kind will often work when the other does not. Do not take thyroid within 6 hours of iron or calcium supplements or you won't absorb the thyroid. It can take 3 to 24 months to see the thyroid's full benefit.

  1. Levoxyl or Synthroid (Rx)—(L-Thyroxine) 50 mcg—(100 mcg = .1 mg). See paragraph below and thyroid information above.
  2. Armour Thyroid (Rx)—30 mg (1/2 grain = 30 mg) (natural thyroid glandular). If #37 (Cortef) is checked, begin the Cortef and/or adrenal support 1-7 days before starting the thyroid. See paragraph below and thyroid information above.

For both of these 2 forms, take ½ tablet each morning on an empty stomach for 3-7 days and then 1 tablet each morning. Increase by ½ to 1 tablet each 1 to 6 weeks (till you're on 3 tablets or the dose that feels best). Check a repeat Free T4 blood level when you're on 3-4 tablets a day (or your optimum dose) for 4 weeks. If okay, you can continue to raise the dose by ½ to 1 tablet each morning each 6 to 9 weeks to a maximum of 5 a day and then recheck the Free T4 4 weeks later. Adjust it to the dose that feels the best (lower the dose if shaky or if your resting pulse is regularly over 88/minute). Do not go over 5 tablets a day without checking a Free T4 blood level and discussing it with your doctor (although it may take as many as 10 a day to see the optimal effect). When on your optimum dose, you can often get a single tablet at that strength. If your energy wanes too early in the day, you can also take part of your thyroid dose between 11 AM and 3 PM. Some people find that taking part of their thyroid dose at night feels better. You can divide your thyroid dose through the day to see what feels best.


  1. Iodine—Iodoral tablets from Optimox ½-1 a day for 2-4 months if you have daytime body temperatures Under 98.3 degrees or breast or ovarian cysts. It contains 12.5 mg iodine (iodine 5 mg & iodide7.5 mg). May flare Hashimoto's Thyroiditis and rarely may suppress thyroid function (with long term use).
  2. Cytomel (Pure active T3) (Rx)—5 and 25 mcg tablets or Compounded Sustained Release T3 (Rx). In Fibromyalgia, resistance to normal thyroid doses may occur and patients often need very high levels of T3 Thyroid to improve. Dr. John Lowe's research group feels that the average dose needed in FMS is 75-125 mcg each morning—much higher than your body's normal production. Because we are often going above normal levels with T3, the risks/side effects noted above increase. Because of this, if you have risk factors, it is more important to consider an exercise stress test to make sure your heart is healthy (i.e., no underlying Angina) before beginning this protocol. Also, consider a Dexa (Osteoporosis) Scan each 6 to 18 months while on therapy. There may be initial bone loss the first year, then increased bone density. Bone density may decrease at 6 months and then increase after that. This having been said, in our experience this therapy has been quite safe and, in some FMS patients, dramatically effective. Begin with 5 mcg each morning and continue to increase by 5 mcg each 3 days until you feel well, shaky or you're at 75 mcg a day (whichever comes first) and then increase by 5 mcg a day each 1 to 6 weeks until (whichever comes first): (a) you reach 125 mcg each morning (or 60 mcg if you're over 50 years old unless approved by your physician); (b) you feel healthy; (c) you get shakiness, worsening significant palpitations (occasional "flip flops" are common), anxiety, racing heart, sweating or other uncomfortable side effects. If this happens, lower the dose a bit for 2-4 weeks and then try raising again till you note significant improvement WITHOUT uncomfortable side effects or you tried to raise it 3 times and still became shaky/hyper.

Blood tests for thyroid hormone or TSH are not reliable or useful on this regimen. If you feel no better even on the maximum dose, taper off (decrease by 5 mcg each 3 days until you're at 15 mcg a day. Take 15 mcg a day for 3 weeks and then drop to 5 mcg a day for 3 weeks—then stop).

After being on therapy for 3 to 6 months, some patients can lower the T3 dose or stop it. Feel free to try dropping the dose. If you feel better initially and then worse (beginning more than 4 weeks after starting a new dose), you probably need to lower the dose. If you lose too much weight, try to eat more (and discuss this with your physician) and lower the dose.

Jacob Teitelbaum, MD

is one of the world's leading integrative medical authorities on fibromyalgia and chronic fatigue. He is the lead author of eight research studies on their effective treatments, and has published numerous health & wellness books, including the bestseller on fibromyalgia From Fatigued to Fantastic! and The Fatigue and Fibromyalgia Solution. His newest book (June 10, 2024) is You Can Heal From Long COVID. Dr. Teitelbaum is one of the most frequently quoted fibromyalgia experts in the world and appears often as a guest on news and talk shows nationwide including Good Morning America, The Dr. Oz Show, Oprah & Friends, CNN, and Fox News Health.

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