Thyroid lab tests are the general standard for measuring function and to determine what is or is not working. While these tests can be very effective in helping you discover where the problem might be, they are not perfect. And for those people with Hashimoto’s they can be misleading.
This is simply because all your thyroid numbers may look fine, but you still feel may like crap. Laboratory tests of thyroid function do not account for flare ups and do not really tell you anything about how your immune system is functioning. In a future post, we will take a look at how to better assess your immune system.
The way the thyroid works in the body is kind of like a bucket brigade. Hormones pass the tiny bucket from the brain, to the pituitary gland, to the thyroid gland, to the liver, and finally to the cells of the body.
The body sends a message to the brain and says “Let’s pick it up!” or “Slow your roll!” (speed up or slow down the metabolism). The part of the body that receives this message is the hypothalamus. The hypothalamus delivers the message to the pituitary gland using thyrotropin releasing hormone (TRH). The brain secretes thyroid stimulating hormone (TSH) which tells the thyroid to make and secrete T4 and T3.
The body can only use T3 and only 7% of it comes from the thyroid gland. The body has to convert the rest from T4. This happens in the liver, the gastrointestinal tract, and in other parts of the body like muscles, the heart, and nerve cells.
So, if your liver isn’t working properly or you have gastrointestinal issues like leaky gut or unhealthy gut flora (bacteria), or your pituitary gland is tired, or you have too many thyroid binding proteins in your blood from too much estrogen or you have an immune problem, you can wind up feeling lousy. It is not uncommon for people to have more than one of these issues at the same time.
And your test results might look perfect. In my last post I discussed how systems of the body are affected by the thyroid. Here you can see how the opposite is also true. All of these systems affect how the thyroid works.
With Hashimoto’s, a lot of what may be causing your symptoms is an autoimmune attack on different tissues of your body. Often, people with autoimmune disease have multiple tissues being attacked and this has less to do with the thyroid than with the immune system.
Typical Lab range: (see below)
Functional range: 1.8 -3.0 mU/L
Thyroid stimulating hormone (TSH), also called thyrotropin is released by the pituitary gland after the hypothalamus releases TRH (thyrotropin releasing hormone). TSH is the most common and most sensitive marker used to assess thyroid function.
Many laboratories have now taken to doing what is called a “thyroid cascade” in order to save themselves and insurance companies money. Basically, if the TSH is deemed to be in the normal range they will not analyze for T3 or T4 or anything else. The problem is, there isn’t a lot of agreement about what the “normal range” is.
Since 2003, the American Association of Clinical Endocrinologists has recommended that the normal range run from 0.3 to 3.0, versus the older range of 0.5 to 5.5. So, according to the new standards, levels above 3.0 are evidence of possible hypothyroidism, and levels below 0.3 are evidence of possible hyperthyroidism. However, there is disagreement among practitioners, and some follow the older range, others use the newer range.
An important thing to understand about TSH is that it is an inverse number when thinking about thyroid function. The higher it is, the more sluggish, under achieving and, generally, slow your thyroid is. The lower it is, the more hyperactive, overachieving and, generally doing too much your thyroid is. Put another way: High TSH = hypothyroid, Low TSH = hyperthyroid.
TSH levels increase as T4 levels drop and TSH levels decrease as T4 levels rise. The reason this is the most popular test in today’s medical model is because the only treatment offered for thyroid dysfunction is thyroid hormone replacement and that’s what doctors are checking when they test your TSH.
A TSH test alone doesn’t give you information about thyroid pituitary communication, about T4 to T3 conversion in other parts of the body or about whether or not your immune system is attacking your thyroid. One important thing for Hashimoto’s people to understand is that some antibodies can inhibit thyroid function by turning off instead of stimulating TSH receptors on cells. In this case, you will see high TSH and high antibodies.
Laboratory range is somewhere between 0.3 (to 3.0) and (0.5 to) 5.5. That is a huge range and borders on the ridiculous. The lab range values are made based on the general population that goes to the lab.
Most people who go to the lab are taking thyroid hormones or are poorly managed or completely undiagnosed (or all of the above) so this is not really a good measure of optimal thyroid health. Practitioners of functional medicine (like yours truly) look at a narrower range that we and some endocrinologists believe is a much better range for assessing a healthy thyroid.
This range is: 1.8 to 3.0. Notice it is higher on the low end and equal to or lower on the high end. Less is more, people, when comes to monitoring a healthy thyroid.
Typical lab range: 5.4 – 11.5 ug/d
Functional range: 6-12 ug/d
The TT4 test measures both bound and unbound thyroxine levels and is not a good marker for T4 activity when measured alone. Total T4 is increased with lower TSH and is decreased with higher TSH. It is decreased with low TSH when the pituitary gland is not functioning properly (pituitary hypofunction).
Many drugs can alter total T4 levels. In my book Roadmap to Remission I explore these interactions.
Typical lab range: 0.7 – 1.53 ng/dl
Functional range: 1.0 – 1.5 ng/dl
Free T4 is used to measure the amount of free or active T4 in the blood. High with hyperthyroidism, low with hypothyroidism. The drug Heparin can also cause elevated free T4 as can some acute illness. Its also high in an overdose of thyroid hormone.
Typical lab range: 4.6 – 10.9 mg/dl
Functional range: 1.2 – 4.9 mg/dl
On its own, this test is pretty useless. Total T4 and T3 Uptake are both used to calculate this marker (TT4 x T3 Uptake = FTI). Prescription drugs often affect T4 and resin T3 uptake levels in opposite ways (if T4 goes up resin T3 uptake goes down and visa versa). Many of these drugs affect thyroid hormone binding sites on cells. FTI is increased in thyroid hyperfunction and decreased in thyroid hypofunction and when your body needs selenium.
Typical lab range: 60-181 ng/dl
Functional range: 100 – 180 ng/dl
Total T3 gives you the total concentration of T3 in the blood. It is the preferred test for thyrotoxicosis (hyperthyroid condition, like Graves disease). Total T3 can also be useful in identifying problems of conversion from T4 to T3 in body tissue involving the enzyme 5′-deodinase.
This enzyme both converts T4 to T3 and stops T4 from working in the body.
Typical lab range: 24 – 39 md/dl
Functional range: 28 – 38 md/dl
This test measures the amount of sites for unbound T3 to bind on thyroxine-binding proteins. Many medications can cause high or low resin T3 uptake. In my program Healing Hashimoto’s: The 5 Elements of Thyroid Health we explore these interactions. Elevated testosterone or testosterone replacement therapy can reduce the number of these binding sites.
This causes a low T4 measurement because it leaves very few binding sites for thyroid hormone to attach to. In contrast, anything that raises the number of binding sites, like estrogen or birth control pills will cause a pattern of high total T4 and low T3 uptake.
To summarize, T3 uptake is increased with hyperthyroid and with high testosterone. T3 uptake is decreased with hypothyroid and high estrogen levels.
Free Triiodothyronine (fT3)
Typical lab range: 2.30 – 4.20 pg/ml
Functional range: 3.0 – 4.0 pg/ml
This test measures the free T3 hormone levels. This test is rarely ordered by traditional endocrinologists and is usually only used when a patient has hyperthyroid symptoms and the fT4 levels are normal.
Even so, this test can be really useful for finding out what amount of active thyroid hormones are available for the thyroid receptor sites. Free T3 is high in hyperthyroid conditions and low in hypothyroid conditions.
Typical lab range: 90 – 350 pg/ml
Functional range: 90 – 350 pg/ml
This test measures the amount of reverse T3 that is produced (duh!). Reverse T3 is usually produced when there is an extreme amount of stress. For example, a serious car accident, or surgery or really bad chronic stress.
Its no surprise that this is elevated after a stress response or when the body produces high amounts of the stress hormone cortisol. Reverse T3 is low when you have severe tissue damage like a bad burn or laceration or when you have liver disease like cirrhosis.
Thyroid-Binding Globulin (TBG)
Typical lab range: 15 – 30 ug/dl
Functional range: 18 – 27 ug/dl
Thyroid-binding globulin binds thyroid hormones that are circulating throughout the body. It is the main protein for carrying both T4 and T3 in the blood. This test may help determine thyroid problems from things not directly related to the thyroid like drugs, liver disease, infection, stress from surgery, etc.
Many drugs can alter TBG levels. In my book Roadmap to Remission I explore these interactions.
Typical lab range for all antibodies: Above the laboratory range
When these antibodies are present, it means that your immune system is attacking your own tissue. When your body produces thyroid autoantibodies it could create a hypo- or hyper- thyroid state. They may also be elevated if there is thyroid cancer. Some antibodies can attach to TSH receptors, but they don’t cause a response in the thyroid.
These people will complain of low thyroid symptoms, but the TSH might not change at all. In other cases, the antibodies bind to receptor sites and cause the thyroid to be over active. Here you will see high T4, low TSH and high antibodies.
There are 3 autoantibodies that are tested. The first 2 are the most common:
Thyroid Peroxidase Antibody (TPO Ab): This antibody is the one that is usually high in autoimmune thyroid conditions like Hashimoto’s. It is also known as microsomal antibody.
Thyroglobulin Antibodies (TgAb): These aren’t seen high as often as TPO Ab. They are usually ordered when thyroid lab results seem strange because these antibodies can interfere with thyroid hormone production. TgAb is also used to monitor progress after surgery for removing the thyroid in thyroid cancer.
Thyroid-Stimulating Hormone Receptor Antibody (TRAb): This antibody is only ordered when a patient is hyperthyroid. Positive results usually mean Grave’s disease.
Once you have tested antibodies and they are high, you have established that you have Hashimoto’s. Of course, these should be looked at in the context of other tests to determine how your thyroid is functioning.
Testing antibodies again is not that helpful for patients with Hashimoto’s because antibody levels can change throughout the day and may rise and fall without giving you any real relevant information about how well you are managing your disease.
They are also not a god indication of how your immune system is doing.
Antibody levels getting higher is not necessarily a bad thing, it can be an indication that treatment has stimulated a certain aspect of your immune system.
And antibody levels going down is not automatically a good thing, it may not lead to any improvement in symptoms.
The reality of having Hashimoto’s is that, in many cases, you have to take matters into your own hands to get proper care. This condition is one of the most poorly managed conditions in healthcare today. This is certainly true with lab tests.
The best thing to do is to work with a practitioner who knows what they are doing and who can order tests to properly assess you thyroid. This way and you can know if what you are doing is working or not.
Be prepared that you may have to come out of pocket to pay for these tests yourself if your doctor or your insurance company don’t deem them medically necessary.
The good news is that laboratory tests have become much more affordable and some functional medicine practitioners, like myself, pass this savings onto their patients because we believe you shouldn’t go broke to get better.
Interested in learning more? Check out this post for a more complete overview of lab tests fro Hashimoto’s.
Hashimoto’s is a thyroid condition and an autoimmune condition, both issues must be addressed to successfully manage this condition. Please let me know your thoughts and questions, I’d love to hear from you.
Mastering the Thyroid, 2011, Kharrazian, Datis, DC
In my last post I looked at 6 different systems and how they were affected by the thyroid and, how that affected Hashimoto’s patients. This is part 2 of that post. And, as I stated in that post, some of this material comes from Dr. Datis Kharrazian, one of the world’s leading experts in the treatment of thyroid issues using functional medicine and from another book called The Thyroid, A Fundamental and Clinical Text, by Braverman and Utiger.
The reason this is important is because the things that you are feeling are not a coincidence or some random group of symptoms. They are caused by your thyroid not functioning properly.
And often, there is a back and forth relationship where a problem or weakness in one of these systems can actually make the problem in your thyroid worse. This is why a holistic approach that treats these various systems is so important.
In our last post, we looked at these systems:
1. Bones and bone growth
2. Blood sugar metabolism
4. Cholesterol and other fats in the blood
6. Cardiovascular system
9. Maintaining Weight
10. Protein metabolism
11. Red blood cell metabolism
Thyroid hormone has a direct affect on movement through the entire gastrointestinal tract. Thyroid hormones increase intestinal neurotransmitters, increase blood flow to the intestines and support the repair and regeneration of the intestines.
Hypothyroidism can slow movement through the esophagus, can affect muscle function in this area and can affect the nerves that cause movement. Hypothyroidism also has an affect on the vagus nerve and this can lead both directly and indirectly to slowing movement through the intestines.
This can lead to 3 common problems:
1. Constipation: One of the most common complaints of Hashimoto’s and hypothyroid patients is constipation. When the bowels slow and it takes more time to empty.
2. Malabsorption: People with hypothyroid problems and Hashimoto’s can have difficulty absorbing important vitamins, minerals and nutrients from their foods. This can lead to a host of health problems including, low protein, anemias, and vitamin deficiencies. Hyperthyroid patients can experience diarrhea that can also lead to poor absorption.
3. Dysbiosis: Hashimoto’s and hypothyroid people often have issues involving problems in the intestinal tract with overgrowth of yeast, harmful species of bacteria and fungus.
When you add the problems caused by gluten and cross reactivity to the slowing of movement and repair in the intestines you have a recipe for a really vicious cycle. Gluten causes breakdown of the lining, slow transit and slower repair and this means that the damage done is compounded and each makes the other worse.
T4 that is secreted by the thyroid gland is converted by the liver into T3 which then has effects on the body. Patients with liver diseases, like cirrhosis have problems converting T4 into T3. High TSH has also been found to cause an abnormal response in the pituitary gland, which signals the thyroid to release more hormones.
Hypothyroid and Hashimoto’s patients also experience issues involving the liver. A hypothyroid state can lead to problems with detoxification pathways, especially phase II detoxification. This can lead to a clogged liver and more problems with converting T4 to T3. This is the reason why liver detoxification is so important for Hashimoto’s patients whether or not they are taking thyroid hormones.
Many Hashimoto’s patients have issues maintaing a proper weight. For some it is due to a low thyroid state, for others it is due to a hyperthyroid status.
For those who are unable to lose weight, there are several different reasons for this. Thyroid hormones are responsible for metabolic activity, a slower metabolism means an inability to lose weight or, in some cases, weight gain. A hypothyroid state can also slow the the body’s ability to use free fatty acids, when this happens fat can not be broken down.
A slower metabolism and fat not breaking down can both lead to fatigue. Hypothyroidism can also cause less growth hormone to be produced, this can lead to loss of muscle mass and the inability to build muscles.
For Hashimoto’s people who have difficulty gaining weight, their problem is that their thyroid is undergoing an immune attack and is in hyperthyroid state. This can last for an extended period of time. Eventually, in Hashimoto’s patients, they get to a hypothyroid state due to thyroid tissue destruction.
If a patient stays in a hyperthyroid state, then Grave’s disease should be considered and a tissue biopsy should be ordered. Also, in Graves disease TSH autoantibodies will be very high. In Hashimoto’s TPO (thyroid peroxidase) antibodies will be highest, with or without TSH antibodies.
When someone is hypothyroid, serum protein levels may be increased because capillaries dilate and allow larger proteins into the bloodstream. Albumin also breaks down more slowly. This can be seen in elevated protein in both the blood and the urine.
A hypothyroid state can lead to several different types of anemia.
Normocytic normochromic anemia: Hypothyroidism can cause a decrease in the production of the hormone erythropoeitin and this may cause this type of anemia. There are about 14 different kinds. For this treatment should be focused on the thyroid.
Macrocytic anemia: Low thyroid activity can lead to this because of a decrease in absorption of vitamin B12 and folic acid caused by a decrease in hydrochloric acid. For this, one must rule out the autoimmune condition below and if it is not autoimmune supplement with B12, folic acid and, possibly hydrochloric acid.
Pernicious anemia: This is an autoimmune disease caused by an autoimmune attack on intrinsic factor which is responsible for helping the body break down and absorb vitamin B12. One of the realities of autoimmune disease is that there are sometimes multiple tissues being attacked.
In about 12% of Hashimoto’s patients, there is also an autoimmune attack on intrinsic factor. If you suspect this type of anemia, an Intrinsic Factor Autoantibody test can be ordered. (IF ab). If this is positive, then they have pernicious anemia. These people respond better to B12 injections.
Iron deficiency anemia: Hypothyroidism can also affect iron absorption because of decreases in stomach acid and excessive blood loss from progesterone receptor site resistance. If iron is deficient, TIBC (total iron binding capacity) should be checked. This will be elevated in iron deficiency and is a good marker to see early iron deficiency. For this, supplement with iron, hydrochloric acid and, possibly, vitamin C to enhance absorption.
Whenever you see an abnormal pattern in a CBC (complete red and white blood cell count) then the thyroid should be evaluated. And when someone sees a thyroid issue, a CBC should always be evaluated.
And here is why this matters: if a patient is anemic, they are not getting enough oxygen to their cells and nothing you do is going to be effective. If you don’t fix this, all the treatments that you attempt will be exercises in futility because the cells of the body are not being powered properly.
The body is not a machine with a series of unrelated parts. It is a group of inter-related ecosystems that all affect one another. When treating Hashimoto’s, it is important to understand these relationships and to work on healing and balancing the body. This will lead to faster, better and more long lasting results. This is why I created Hashimoto’s Healing: The 5 Elements of Thyroid Health. This system gives you the tools to do this and to radically improve your results in managing and healing your Hashimoto’s.
Kharrazian, Datis, DC Mastering the Thyroid, 2011
The Thyroid, A Fundamental and Clinical Text, Ninth Edition, Lewis E. Braverman & Robert D. Utiger, 2005, Lippincott Williams & Wilkins
Green JR, Diminished TSH repines to TRH stimulation in patients with hepatic cirrhosis dispute subnormal T3 levels. Z. Gastroenterol. 1979:17(7):447-51
Saha B, Maity C. Alteration of serum enzymes in primary hypothyroidism. Clin Chem Lab Med. 2002;40:609-611
In today’s health care system there are many specialists. It is easy to lose track of the fact that the body is a group of ecosystems, all interconnected and interacting. The thyroid is a perfect example of all these complex interactions and connections.
I have been a long time student of Dr. Datis Kharrazian, one of the leading experts of the treatment of the thyroid with functional medicine and author of the book, Why Do I Still Have Thyroid Symptoms When My Lab Tests Are Normal?. (This book should be required reading for anyone diagnosed with Hashimoto’s). The material in this post comes from some of my studies with him and from a book called The Thyroid, A Fundamental and Clinical Text, by Braverman and Utiger.
The body is not just a bunch of unrelated machine parts. Everything is connected in some way.
When you have Hashimoto’s, chances are good that you have symptoms in some other areas of your body. Read on and you will understand why.
That’s right, 11. In this 2 part blog post we will introduce each one of them briefly and also discuss how these connections affect Hashimoto’s patients. I will also be exploring all of these in more depth in future posts. Please let me know what interests you.
1. Bones and bone growth
2. Blood sugar metabolism
4. Cholesterol and other fats in the blood
6. Cardiovascular system
9. Maintaining Proper Weight
10. Protein metabolism
11. Red blood cell metabolism
Low TSH or a hyperthyroid state can lead to an increased lifetime risk for fractures, even after TSH has become normal again.
In children, a lack of thyroid hormones will affect normal growth.
Adult hypothyroid and some Hashimoto’s patients tend to have higher than normal bone density. But, this higher density does not necessarily mean good bone quality: there may be issues with collagen, bone turnover, the size of mineral crystals and bone structure. So, even though the bones are more dense, these people may still be at risk for fractures because the bone quality is really poor.
IL-6, an inflammatory cell commonly seen elevated in Hashimoto’s patients can also lead to bone loss.
Blood sugar is controlled by the pancreas. The pancreas and thyroid are both part of the endocrine system. The endocrine system is made of many feedback loops and their various hormones all “talk” to one another and make changes to the body to try and keep things in balance.
These systems also work in both directions. They influence each other. In the case of sugar, insulin is released by the pancreas to help the cells of the body absorb sugar so that it can be used. And the adrenals release cortisol to help sugar get absorbed by the cells of the body.
A hypothyroid state leads to a slow absorption of glucose, a slower breakdown of insulin, a decrease of the speed at which glucose is absorbed in the gut, a lower glucose to insulin response and, finally, less glucose in the cells for the body to use. All of this means less energy to power your cells and brain and more fatigue.
To make matters worse, all of this affects the adrenal glands and the hypothalamus-pituitary-adrenal axis (HPA axis). In order to try and fix the problem of not having enough sugar, the adrenal glands release the stress hormone cortisol to increase glucose in the cells.
Every Hashimoto’s patient has some degree of the sugar imbalance described above. If you are skinny, its probably hypoglycemia. If you are overweight it may be insulin resistance or metabolic syndrome. If you feel better after you eat, you are hypoglycemic. If you are tired after you eat, you have insulin resistance.
All of this creates a vicious cycle that can really stop you from getting better. All Hashimoto’s patients must take blood sugar problems seriously. You won’t get better unless you do. In my six week program you will discover how to do this. Click on the link to the right get my 4 video series and learn more.
Thyroid and the Brain
Thyroid hormones are very important for healthy brains. In the adult brain, thyroid hormones have shown the ability to help the brain grow and change and to help the brain age in a healthy way.
Hashimoto’s patients know about “brain fog”. There are many reasons for this, the principle ones being inflammation of the brain and a breakdown of the blood brain barrier. The proteins that protect the brain (called zonulin) are the very same proteins that protect the gut. So if you have leaky gut, there is a good chance that you also have leaky brain.
When your brain is inflamed you get brain fog and it degenerates. There are 2 primary symptoms:
It is no surprise that the most common drugs prescribed with Hashimoto’s are anti-depressants. You absolutely must support your brain if you have these symptoms.
Brain fog is a brain cell activated immune response. The immune system in the brain is not specialized and sophisticated like the immune system in the rest of the body. Brain immune cells (called microglia) are kind of like paranoid chihuahuas with automatic rifles. They tend to over react quickly and when they do you get lots of inflammation (brain fog).
In some patients, thyroid hormone may improve brain fog. In others it won’t. You have to reduce inflammation in the brain in a different way. In my 6 week course you learn how to do this and what herbs and supplements can really help with this. One important herb that is used is turmeric. Click on the link to the right to get my 4 video series and learn more.
Thyroid and Cholesterol
In hypothyroid conditions, both the breakdown and the use of cholesterol by the body are depressed. But the breakdown is much slower, so the net result is higher cholesterol, triglycerides and LDL. This may be slower because of a decrease in the breakdown of fats once they leave the liver or in a decline of LDL receptors.
This is why some Hashimoto’s patients also have high cholesterol, triglycerides and LDL (and sometimes low HDL). Once they get their thyroid under control, it is not unusual to see their cholesterol, LDL and triglycerides return to normal as well.
Thyroid and Gall Bladder
Gall bladder function is also adversely affected in hypothyroid conditions. Studies have shown that the gall bladder gets larger and doesn’t contract normally.
Studies also report an increase in the number of gallstones and stones in the common bile duct. One reason they think this might be happening is because the thyroid hormone thyroxine relaxes the gall badder’s opening (called the sphincter of Oddi). This makes bile not flow normally, and makes the possibility of stones forming in the bile duct more likely.
Bile also helps to break down cholesterol so when there is less bile, less bile flow and gall bladder is slow and sluggish you have the perfect situation for stone formation.
Thyroid and Cardiovascular System
Thyroid hormones have a big impact on many functions of the arteries and veins in the body. Low T3 levels have been linked to diseases of the blood vessels. One of the most common problems that Hashimoto’s patients have is cold hands and feet. Hair loss and fungal nail growth can also be signs of poor blood flow.
Low thyroid function means less nitric oxide is available in the blood vessels, this can lead to a break down of the vessels themselves. When you add in the problems with cholesterol and you have a recipe for plaque clogging the arteries.
For those patients taking levothyroxine, some of these problems have been shown to be reversed by the medication.
All those symptoms that you experience are not by accident or some coincidence. There are very clear reasons why your body is experiencing what it is going through. The goal of this blog, my website and my program are to help you to understand how all this works in simple terms, so that you can discover how to get control of your health.
That’s why I created my program Healing Hashimoto’s: The 5 Elements of Thyroid Health. To give you all the information and solutions in 1 place, to teach you how to better manage your Hashimoto’s and to make the goal of having more goods days than bad ones easy to reach.
Muller MJ, Burger AC, Ferrannini E, et al. Glucoregulatory function of thyroid hormones; role of pancreatic hormones. Am J Physio. 1989;256:E101-E110
Flavin RSL, et al. Regulation of microglial development: a novel role for thyroid hormones. The Journal of Neuroscience. 2001;21(6):2028-2038
Oge A, Sozmen E, Karaoglue AO. (2004) Effect of thyroid function on LDL oxidation in hypothyroidsim and hyperthyroidism. Endocr Res 2004; 30:481-489
Laukkarinen J, Kiudelis G, Lempinen M, Raty S, Pelli H, Sand J, Kemppainen E, Haglund C, Nordback I. Increased prevalence of subclinical hypothyroidism in common bile duct stone patients. J Clin Endocrinol Metab. 2007 Nov;92(11):4260-4. Epub 2007 Aug 28
Napoli R, Guarasole V, Angelini V, et al. Acute effects of triiodothyronine on endothethial function in human subjects. J Clin Endocrinol Metabl. 2007;92(1):250-4
Taddei S, Caraccio N, Virdis A, et al. Impaired endothelium-dependent vasodilation in subclinical hypothyroidism: beneficial effect of levothyroxine therapy. J Clin Endocrinal Metab. 2003:88(8):2731-7
Mastering the Thyroid, Datis Kharrazian, 2011
The Thyroid, A Fundamental and Clinical Text, Ninth Edition, Lewis E. Braverman and Robert D. Utiger, 2005 Lippincott Williams and Wilkins