Dr. Pamela Smith gave a detailed talk regarding hypothyroidism at the 23rd Annual World Congress on Anti-Aging Medicine on Dec. 13, 2015 in Las Vegas. As a lack of thyroid hormones is one of the causes of premature aging, it is important to pay attention to your thyroid hormones. Here I am summarizing the highlights of this talk.
Thyroid disease, particularly low thyroid hormone levels, called hypothyroidism is very common in the population. Part of the problem is that in 72% of the world population dietary iodine is insufficient to provide adequate amounts of iodine to the body that is required for thyroid hormone production in the thyroid gland. The US Institute of Medicine has recommended 150 micrograms of iodine intake every day. Japan with its emphasis on seaweed intake is one of the few countries where thyroid deficiency is extremely low (Ref.1).
But apart from dietary factors there are many other factors that can lead to insufficient amounts of circulating thyroid hormones (see below).
The production of thyroid hormones
The thyroid gland produces the thyroid hormones by adding iodine atoms into the amino acid L-tyrosine to make thyroxin (T4) and triiodothyronine (T3). T3 is the main active hormone, which is about 5-times more powerful than T4. There is a feedback cycle between thyroid hormones, the hypothalamus and the pituitary gland. Both the hypothalamus and the pituitary gland have thyroid hormone receptors that sense the level of T3 and T4 and can modify the production of these hormones. The majority of T3, which is the main active thyroid hormone, is produced by conversion of T4 into T3 by a selenium-dependent enzyme.
Most of the thyroid hormones are bound in the blood by thyroid binding globulin. Only the free T3 and free T4 are metabolically active and will affect the metabolism of our body cells. The delicate balance can be easily disrupted. Oral contraceptives and sex hormone replacement therapy can increase the amount of circulating thyroid binding globulin, thus creating a thyroid hormone deficiency state, as the free T3 and free T4 are diminished.
Other factors influencing circulating thyroid hormones
- Low adrenal gland hormone activity can occur simultaneously with hypothyroidism. On the other hand, when thyroid hormones are low by themselves, the adrenal glands often compensate by producing more cortisol to offset some of the symptoms of hypothyroidism.
- An enzyme located in the liver, kidneys, pituitary gland, hypothalamus and brown fat is necessary for conversion of T4 to T3, the more active thyroid hormone. Anything that interferes with this conversion leads to hypothyroidism. Over the years medical research has identified many factors that interfere with this process. For instance, there are trace elements necessary for this enzymatic reaction, like selenium and zinc; if they are low in the diet, low T3 will be the result. But other nutrients, if missing, will also interfere with T4 to T3 conversion: iodine, iron as well as vitamins A, B2, B6 and B12.
- Several medications can also interfere with the conversion of T4 to T3: we already mentioned birth control pills; others are estrogen, lithium (patients with bipolar disorder are often on this), phenytoin, theophylline, beta blockers (such as propranolol), chemotherapy and clomipramine.
- But dietary factors can also lower T3 due to a lack of conversion from T4:too many cruciferous vegetables, a low carbohydrate diet, low fat diet, low protein diet, excessive alcohol use, walnuts and soy. In a study where the effects of soy were examined 37 adults on a high soy diet over three months 50% developed hypothyroidism. When the soy diet was stopped it took one month to normalize the thyroid function (Ref. 2).
- There is no end of factors that cause low T3 because of the inability to convert from T4: chronic inflammation due to cytokines, diabetes, aging, poisoning with heavy metals like mercury, lead and cadmium (cigarette smoking), fluoride, pesticides, exposure to radiation and stress. Other toxic substances that enter the body can interfere with the same T4 to T3 conversion process: dioxins, phthalates (chemicals added to plastics) and PCB. But excess calcium and copper (copper salts could come from spraying of organic fruit) can also lead to low T3.
- Other hormones can disbalance the equilibrium and cause low T3 because of a lack of conversion from T4: too much stress, which causes cortisol from the adrenal glands to rise. Surgeries associated with the same stress response (high cortisol levels) also have been shown to cause low T3.
- There is another conversion process that has been shown to lead to lowered T3: it is called “reverse T3 (rT3)”. rT3 is an inactive form of T3, which blocks thyroid receptors and renders T3 less active. rT3 is particularly important in stressful situations and in athletes who engage in extreme exercise. In these individuals T3 and T4 blood tests are normal, TSH is suppressed and rT3 is elevated. That’s how the doctor can diagnose this condition. Other conditions that lead to high reverse T3 are: aging, diabetes, exposure to free radicals (chemotherapy or radiation in cancer treatment), fasting, prolonged illness, toxic metal exposure, inflammatory cytokines, depression and anxiety, bipolar disorder, Alzheimer’s and Parkinson’s disease, chronic fatigue syndrome and fibromyalgia.
- After all this negative news it is almost a wonder that the thyroid is still doing its work! Since we know the risk factors, it is important to be aware that certain supplements and dietary habits can help to increase the conversion from T4 to T3. Here is a list of those that help: iodine, iron, zinc, selenium, potassium, Ashwaganda, and a high protein diet. Other positive factors are vitamins A, B2 and E; growth hormone, testosterone, insulin, glucagon, melatonin and estrogen (high dose).
Symptoms of hypothyroidism
There was an overwhelming amount of information about signs and symptoms of hypothyroidism that was reviewed. I can only highlight some of the more common symptoms here. It is important to know that some of these signs and symptoms occur several years before the lab values become abnormal; this is particularly true of the “eye brow sign” and the thinning of eyebrows is a pointer to hypothyroidism!
Depression, weight gain, constipation and migraine type headaches can be early non-specific signs of hypothyroidism. Women often present with irregular periods. Other symptoms are: decreased memory and inability to concentrate, anxiety/panic attacks, muscle and joint pains, a puffy face, swollen eyelids, decreased sexual interest, and sleep disturbance. Sparse, coarse, dry hair; missing hair confined to the outside 1/3 of both eye brows (eye brow sign) and carpal tunnel syndrome are also associated with a lack of thyroid function. Often there is also a loss of eyelashes or eyelashes that are not as thick. When blood tests show high cholesterol, iron deficiency anemia or vitamin B12 deficiency this should prompt the physician to order thyroid tests.
Blood tests for hypothyroidism
TSH, free T3, free T4, reverse T3 and thyroid antibodies need to all be ordered to have a complete documentation of what is going on. Among the thyroid antibodies these three types need to be ordered: antithyroglobulin antibody, antimicrosomal antibody and antithyroperoxidase (anti-TPO) antibody. There are a number of more studies that an endocrinologist would order in difficult to diagnose cases. Thyroid antibodies are an important cause of hypothyroidism in the US and can be due to Hashimoto’s thyroiditis, an inflammatory condition of the thyroid gland. Some people have autoimmune antibodies against adrenal gland tissue. There are also patients who have gluten sensitivity, and they may produce these autoantibodies to both the adrenal glands as well as the thyroid gland.
Treatment of hypothyroidism
Treatment for hypothyroidism consists of detoxification, proper nutrition and thyroid hormone replacement.
Detoxification can include intravenous chelation therapy, if heavy metals are involved. In some cases detoxification is all that is needed.
Proper nutrition with a Mediterranean diet and some iodine supplements or seaweed is important. But often the thyroid is damaged by the time hypothyroidism is diagnosed and thyroid hormones have to be replaced.
Replacement of thyroid hormones is best done by desiccated thyroid or compounded thyroid (both T3 and T4). The normalization of the TSH level is taken as the end point and should be below 2.0 (not the lab normal value of below 5); free T3 should be optimally between 3.5 and 4.3 and reverse T3 should be 50 to 150 pg/ml to be optimal.
If reverse T3 is high, the patient will have hypothyroid symptoms, even if T3 and T4 blood tests are normal. Because reverse T3 is derived from T4, the physician will have to lower T4 or take the patient off T4. Replacement with T3 will lead to lower TSH production by the pituitary gland and production of T4 and inappropriate conversion to reverse T3 will decrease.
Depending on what other conditions the patient presents with, it likely will help to eliminate stress, treat selenium and iodine deficiency, treat infections and treat growth hormone deficiency, if present.
There were many more pearls of wisdom in this very comprehensive talk on hypothyroidism, but there is not enough room in this blog to mention all of this. For more info read Dr. Pamela Smith’s book (Ref.3).
The thyroid is one of the main players involved in the maintenance of our health and well being. Hypothyroidism can develop for multiple reasons: inadequate iodine intake, toxins including heavy metals, autoantibodies from gluten or other sensitivity and certain medication usage. It is a fallacy to think that supplements, vitamins and lifestyle choices can “cure” thyroid deficiency. Once the levels are low, thyroid replacement is the only way to reestablish a hormonal balance! The treating physician must consider many factors when replacing thyroid hormones optimally. Desiccated thyroid hormone replacement (containing T3 and T4) is the best type of replacement of missing thyroid hormones. The needs can differ a great deal, as no patient is the same! For best results the treating physician needs to individualize treatment.
Ref. 1: Brownstein, D., “Iodine: Why You Need It, Why You Can’t Live Without It”. Medical Alternatives Press, 2004.
Ref. 2: Kelly, G., “Peripheral metabolism of thyroid hormones: A review,” Alt Med Rev 2000; 5(4):306-33.
Ref. 3: Smith, P. “What You Must Know About Thyroid Disorders”. Garden City Park, NY: Square One Publishers, 2016.
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