Thyroid gland: where it is and what it does

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The thyroid gland is the thermostat of the body. It regulates the rate and intensity of the body’s chemical reactions. The parathyroid glands regulate the amount of calcium and phosphorus in the blood. As it turns out, malfunctions in these glands are not that uncommon and can produce serious problems such as over excitement of the muscle and nervous systems, bony demineralization, high calcium levels, duodenal ulcers, kidney stones, and behavioral disorders. And if left unchecked, they can kill you. Fortunately, there are things you can do to minimize the chances of these problems occurring in the first place, or relieving them through alternative means if you get them.

The thyroid is one of the largest endocrine glands in the body and specifically controls how quickly the body uses energy, how it makes proteins, and the body’s sensitivity to other hormones. The function of the thyroid gland is to take iodine and convert it into thyroid hormones — primarily, thyroxine (T4) and triiodothyronine (T3). Normal thyroid cells accumulate and retain iodide far more efficiently than do any other cells in the body. Most cells don’t absorb iodine at all, but some, including thyroid cancer cells and breast epithelial cells, can to a limited degree. Thyroid cells combine iodine and the amino acid tyrosine (as bound to thyroglobulin) to make T3 and T4. T3 and T4 are then released into the bloodstream and transported throughout the body, where they control metabolism (i.e., the conversion of oxygen and calories to energy). Every cell in the body depends upon thyroid hormones for regulation of their metabolism.

Anatomically speaking, the thyroid is a butterfly shaped gland (two larger lobes connected by a narrower isthmus) located between the Adam’s apple and the clavicle. A normal thyroid gland cannot be felt externally. If a doctor can “see” it or “feel” it when touching the neck with his fingers, it’s enlarged. Under normal circumstances, it’s soft and flat.

When talking about thyroid hormones, we’re actually talking about four bio-chemicals:

• Thyroglobulin is a protein (not a hormone) produced by the thyroid. It is synthesized from amino acids and iodide and stored in the follicular lumen as a colloid and used entirely within the thyroid gland in the production of the thyroid hormones.

• T3 (triiodothyronine) affects almost every physiological process in the body, including growth and development, metabolism, body temperature, and heart rate. Production of T3 and its prohormone, T4 (T3 is actually produced by the breakdown/conversion of T4), is activated by thyroid-stimulating hormone (TSH), which is released from the pituitary gland. As a side note, the 3 in its name refers to the fact that it contains 3 iodine atoms.

• T4 (thyroxine, AKA tetraiodothyronine) is the prohormone from which the body creates T3. It is synthesized from residues of the amino acid tyrosine, found in thyroglobulin. Every cell in the body depends upon the thyroid hormones T3 and T4 for regulation of their metabolism. The normal thyroid gland produces about 80% T4 and about 20% T3. However, T3 is about four times “stronger” than T4. T4 is converted to T3 in body cells. This allows the body to fine tune the metabolic regulating capabilities of T3 and T4. As with T3, the 4 in T4’s name refers to the fact that T4 contains 4 iodine atoms.

• Calcitonin is produced in the parafollicular cells and regulates calcium levels in the blood (to a minor degree), along with the parathyroid glands (the main regulator). It lowers blood calcium and phosphorus by decreasing the rate of re-absorption of these minerals from bone.

Thyroid chemistry is an iodine-based chemistry; iodine must be ingested because it can’t be manufactured in the body; it is an element, not a compound. In fact, follicular cells actively trap virtually all iodine/iodide molecules in the body. Any iodine you ingest is trapped exclusively by cells in the thyroid to be used for manufacturing thyroglobulin and, ultimately, T3 and T4. This fact is exploited by endocrinologists when it comes to treating several thyroid disorders. If iodine is not present in sufficient amounts, the body will develop a benign goiter (enlargement of the thyroid) over time. It is common in areas where iodine does not naturally occur in food. In the early 1900’s, Western countries began adding iodine to salt to combat this problem. And it worked, in the sense that goiters are now uncommon in the Western world.

Thyroid-stimulating hormone (TSH) from the anterior pituitary regulates the processes via a negative feedback loop. That is to say, thyroid releasing hormone (TRH) from the hypothalamus stimulates the pituitary to release TSH into the bloodstream, which stimulates thyroid follicular cells to add iodine to the amino-acid (tyrosine) component of thyroglobulin (which, once again, is stored as colloid within the lumen of the thyroid follicles).

Once converted, the T3 and T4 hormones are released into the bloodstream. This arrangement essentially works as a reserve system for thyroid hormones, allowing it to release active hormones into the body on an as needed basis. As more thyroid hormones are produced, blood levels of T3 and T4 rise. Ultimately, these hormones make their way through the bloodstream back to the hypothalamus, telling the hypothalamus that enough is enough and to stop releasing TRH, which stops the pituitary from releasing TSH — shutting down the cycle.

Thyroid hormones regulate the following activities:

• Oxygen uptake (they upregulate it).

• Gross basal metabolic rate (they upregulate it).

• Maintenance of body temperature.

• Intracellular metabolism (microscopic protein synthesis, lipid breakdown, and cholesterol breakdown.) Patients who are hypothyroid, for example, will have higher levels of cholesterol in the blood because of reduced thyroid up regulation. Patients who are hyperthyroid will often be thin and have lower levels because of too much up regulation.

• Growth and development; that is, body growth rate and nervous system development.

• Thyroid hormones also enhance the effects of catecholamines, accounting for high blood pressure, nervousness, sweating, and fast heart rate in hyperthyroid patients.

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  1. thanx for article. Have come to believe that most current docs, maybe unwittingly, are participating in organized execution of the population control directive on Georgia Guidestone. Local hospital says, “voted #1 residency program in nation”: how?why? Last few crops of docs there are SCARY, not very bright, No independent thought! Of self, 40y/a CT showed R lobe “marginally func-tional”, 30y/a told “don’t make T3”, 20y/a developed pancake goiter: still have, untreated. Doc,30y/a, “we don’t give Cytomel to women, only men w/ED”. No doc has Rx’d ANY treatment since. They don’t listen!

  2. EXACTLY seven years later, and nothing has changed from the medical comminity’s perspective, at least where I live….

    Holtorf’s Clinics across the country are now “experimenting” on one in every eight women who come to them, FOR PROFIT. (SRT3 doesn’t work, and their patients are ending up in emergency rooms.)

    More and more children are being added to the rolls of those abused, neglected, and living shortened lifespans.

    My Mom, aged 88 years, is now ingesting a T4-only med; *I*’ve known she’s had a “thyroid problem” for four-plus years. She’s only getting a TSH test once a year, because her GP can’t “justify” anything else (her TSH has NOT been tested since the T4-only med was prescribed). Ummm, geee. Is that part of the AACE’s “Guidelines”???

    My daighter’s “thyroid problem” (autoimmune disease) remains ignored; it’s more important to her medical community to perpetuate her “bipolar” diagnosis, have her ingest meds that destroy her liver, and create “other” health “problems”, for which there are “other” specialties and “other” meds. Her insurance won’t cover the tests (not that anybody would correctly interpret her results). Her diet has changed, and she’s doing better. Still, chances are that her liver is probably converting her own T4 into Reverse T3, which her cells can’t use.

    You’d think that, somewhere, sometime, one of all these doctors would actually ask about FAMILY HISTORY! No. At least my daughter knows how to respond if she’s ever asked….

    Seven years after writing the above comment, NOTHING has changed about THE “acceptable, standard of “care”. It still permeates all specialties, and it’s still promoted, perpetuated and perpetrated by insurance companies. It’s certainly NOT “acceptable” to me….

  3. The lack of education about what a healthy thyroid does never ceases to amaze me; this article was insightful, even though, from my perspective, it is very limited in scope. The lack of education of medical professionals about what T4 and T3 actually do, or don’t do, throughout the entire body and brain is … appalling! No, I don’t describe my “consent” as “informed” prior to destroying my thyroid with radioactive isotopes.

    I have no thyroid, so I can’t be hyper or hypo, yet I am considered “hypo” by the medical community. I am “hyper” when ingesting T4, because I can’t convert it (INsufficient T3 at the cellular level is actually “hypo”), and I’m “hypo” if I don’t ingest T4 (as far as the medical community is concerned). I have no thyroid, yet I have “thyroid disease” because I have antibodies (as far as the medical community is concerned). Antibodies prevent me from using the thyroid hormone I now must ingest for the rest of my life. I can’t convert T4 into T3, yet every individual cell needs T3. Doctors in every concievable specialty think they can “treat” me with a T4-only medication based on a pituitary lab test result!

    To the author of the above article:

    My TSH lab test result is 0.00, on purpose, with good reason (thyroids grow back, more often than not; when you swallow RAI like I did, they grow back, more often than not, malignant). We don’t want my future malignant thyroid producing malignant hormones and sending them throughout my body, and we don’t need my pituitary telling my currently non-existent thyroid to “wake up”. 21st Century medical SCIENCE proves that anyone who has no thyroid and a TSH lab result other than 0.00 is UNDERmedicated (probably not ingesting any, or too little, T3).

    Any T4 lab test result for me also is 0.00, as proof that I have no thyroid to make any and as evidence that I don’t ingest any (because I can’t convert it). A T4-only, or mostly-T4, medication will “overdose” me on T4, precisely because it provides me with none, or too little, T3. Ingesting T3-only medication means any T3 lab test result will be “too high”, precisely because it ONLY tests what I am ingesting, NOT what is actually making it INto my cells.

    21st Century medical SCIENCE proves that women need more T3 than men, but labs provide reference ranges that are unisex. NO lab provides appropriate reference ranges when one has no thyroid. Rigorously screened, healthy volunteers had ZERO antibodies, so ONE is TOO MANY, yet labs provide multiple reference ranges to the contrary. When you have NO thyroid and DO have antibodies, labs’ reference ranges mean NOTHING! Yet the medical community is perfectly satisfied “treating” a THYROID problem based solely on a PITUITARY lab test result, from blood drawn once a year, with a T4-only medication that allows them to “control” that PITUITARY lab test result, regardless of their patients’ actual health. If you are the one without a thyroid and with autoimmune disease, this “acceptable” standard of “care” is the very definition of insanity: abuse, neglect, and homicide (suicide if you participate by following doctors’ advice). I no longer participate in my abuse or neglect, precisely because it will cause my death (suicide). Yet the medical community thinks they can mandate my consent to be abused and neglected, and I’m the one declared insane when I refuse to voluntarily participate in my abuse and neglect by agreeing to ingest a medication I know will kill me. Hello? The medical community’s (all specialties’) reliance on 20th Century medical MYTH (a singular TSH lab test result) in the face of 21st Century medical SCIENCE is 100% profit-motivated, and has NOTHING to do with actual medical “care”.

    An extreme, severe, and illogical, yet perfectly “acceptable” standard of “care”, practiced by every doctor (who doesn’t understand that every individual cell NEEDS T3) in every specialty, as promoted, perpetrated and perpetuated by so-called specialists (endocrinologists) through various insurance companies, for one in every eight women, results in abuse, neglect and premature death. IF I am denied my T3 based on a pituitary and/or T4 and/or T3 lab test result of any kind, I’ll die, within two days, yet killing me is THE “acceptable” standard of “care”. Hello? Even the cardiologists could not explain my congestive heart failure, and they had no clue how to “resolve” it. I never had, and still do not have a PITUITARY “problem”; I can’t have a THYROID “problem”, since I have NO thyroid.

    My education level is a high school diploma with “some” college; if *I* can understand that I can’t convert T4 into T3 and that antibodies prevent my cells from getting the T3 they NEED, even if I ingest T3, why can’t doctors? If *I* can understand that antibodies are evidence of autoimmune disease and that T3 is NOT a treatment for my autoimmune disease (it’s only replacing what I can no longer produce without a thyroid), why can’t doctors? If *I* can understand that taking “too much” T3 has NO side effects (excess unable to be used by my cells gets processed out like any other waste, the complete opposite of ingesting “too much” T4), and that I am wasting my T3 and the money I spend on it, IF I ingest “too much”, why can’t doctors? If *I* can understand that taking “too much” T4 (ANY T4 in my case) will cause my premature death, why can’t doctors? Most importantly, if I could convert T4 into T3, and I can understand that T3 converted from T4 will never be enough T3 because I have NO thyroid, why do doctors believe that a T4-only medication is a “cure-all” for every person with NO thyroid???

    Unfortunately, ignorance by so-called professionals “practicing” every specialty perpetuates the abuse, neglect and, eventually, the premature death of one in every eight women and only God knows how many men.

    I’m grateful my doctor treats ME, the actual patient, and not my pituitary lab test result. It’s really, really sad, shameful, and inexcusable that my doctor is one of very few who actually practices medical SCIENCE.

    IF doctors have IQ, they aren’t demonstrating it when they “practice” THE “acceptable” standard of “care”; from my perspective, they are demonstrating their lack of education, and their greed, at their patients’ physical, mental, emotional, and financial expense. Since I believe all abuse is Spiritual abuse, their actions also have Spiritual consequences, for them and their patients. IF doctors continue to NOT educate themselves with 21st Century medical SCIENCE (every individual cell NEEDS T3, women NEED more T3 than men, and labs’ reference ranges are grossly skewed by greed and “acceptable” levels of illness), well, I guess, “You can’t fix stupid”. How ironic that doctors know Cytomel exists, yet they have no clue how much to prescribe or how to write instructions for ingesting it!!!

    I apologize for the length of my “comment”; guess I needed to “vent” my disgust with yet another article that purports to explain my “thyroid” problem and it’s supposed resolution, when I have NO thyroid AND autoimmune disease. I remain grateful for my doctor; I’m really, really, really, screwed when she retires…..

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