Hello people! Last week was a light one on dark chocolate (ha ha?) but as promised, today marks the start of a new series on thyroid disease. If you’re wondering why I, a shrink, would care about the thyroid, the answer’s simple: because when it’s a problem, it’s a real problem, because it can affect nearly every aspect of your life, including your mental health. But when it comes to the thyroid, you’re about to find out that that’s where the simplicity ends.
Before we can talk about how the thyroid can affect you, first we have to talk about what it is. The thyroid is a butterfly-shaped endocrine gland that’s found in the forward aspect of the middle of the neck, just below the larynx, or voice box. Its two lobes, left and right, lie on either side of the windpipe, and are each about the size of a halved plum. These lobes are analagous to the wings of the butterfly, and they are joined by a small bridge of thyroid tissue called the isthmus.
Notice I said it was an endocrine gland? The endocrine system is made up of glands that make hormones, which are the body’s chemical messengers- they carry information and instructions from one set of cells, glands, and organs to others. In doing so, the endocrine system influences almost every cell, gland, organ, and function of the body. That’s what makes the thyroid so important- because it’s a big part of the endocrine system, along with the other major glands, including the hypothalamus, pituitary, parathyroid, adrenal, pineal, and the ovaries and testes.
The hormones made by the various glands of the endocrine system are released into the bloodstream, and they travel to cells in other glands and organs where they help control organ function, mood, growth and development, metabolism, and reproduction. The amounts of hormones produced and released is highly regulated, and depends on levels of other hormones already in the blood, other minerals like calcium in the blood, the blance of water and other fluids in the body, and external factors such as stress and infection, just to name a few. Because hormone production and levels are all interlinked- one dependent upon another- it’s important that these levels remain normal. Too much or too little of any one hormone affects production and release of multiple others, so it can affect several organ systems, and cause nearly endless physical and emotional symptoms. This can make you feel very ill, a little “off,” or anything in between.
The Pituitary Gland
Even though this series is on the thyroid, I can’t rightly talk about it, or the endocrine system, without mentioning the pituitary gland. The pituitary is a pea sized gland located at the base of the brain, but don’t let its size fool you, because mighty things can come in small packages. In fact, the pituitary is often called the “master gland,” because the hormones it makes control many of the other endocrine glands. The pituitary also happens to be one of my faves- and it should be one of yours too- because it secretes endorphins, the body’s natural feel good chemicals, the ones that act on the nervous system to produce feelings of pleasure and reduce feelings of pain.
The pituitary gland makes many other hormones, including growth hormone, which stimulates the growth of bone and other body tissues; prolactin, which activates milk production in breastfeeding women; corticotropin, which stimulates the adrenal gland; antidiuretic hormone, which helps control the balance of body water through its effect on the kidneys; and oxytocin, which triggers uterine contractions during labor. But the pituitary hormone that’s most germaine to today’s topic is thyrotropin, more commonly known as thyroid-stimulating hormone, or TSH. Once secreted by the pituitary, TSH, as its name suggests, stimulates the thyroid to synthesize and release thyroid hormones.
In response, the thyroid produces thyroxine and triiodothyronine, more commonly known as T3 and T4, respectively. These hormones control the rate at which cells burn fuels from food to make energy. They basically regulate the body’s metabolism- the rate at which the cells of the body use and store energy. I’ll get into that in a moment, but because they control such a basic function, you can clearly see that thyroid hormones are essential for all the cells in your body to work normally. If that weren’t enough, they also play a role in bone growth and development, as well as that of the brain and nervous system. Just to add another level of complexity, there are also four other tiny glands attached to the thyroid gland called the parathyroids. They release parathyroid hormone, which, along with help from another thyroid hormone called calcitonin, controls the level of calcium in the blood. And if you remember, calcium is one of those minerals in the blood that controls the production and release of other hormones. Yikes!
Believe it or not, this is as simplified as the endocrine system- and the thyroid- really gets, people, so if you’re thinking all of this is super complicated, you cannot even imagine if you just go by this! As a matter of fact, there’s an entire (underappreciated) specialty medical field devoted to this alone… so thank you endocrinologists!
Thyroid Function: Metabolism
As I mentioned before, thyroid hormones regulate the body’s metabolism. Many people think that just means how many calories you burn, but metabolism is a complicated process, one that’s happening 24/7, no matter what you’re doing. That’s even reflected in its literal meaning, which is “a state of change.” Your body relies on metabolism to carry out all of its functions, whether it’s storing or burning fat, regulating sugar levels, or keeping your neurons firing; so metabolism has a huge impact on your health. The three main purposes of metabolism are: the conversion of food to energy to run cellular processes, the conversion of food/ fuel to the body’s building blocks, and the elimination of metabolic wastes.
This intricate involvement with such an important, universal bodily process is why diseases of the thyroid have such an extreme and varied impact on human health. But (thankfully) all of it boils down to two basic conditions: having too much thyroid hormone results in a condition called hyperthyroidism, while having too little thyroid hormone is called hypothyroidism. Generally speaking, in hyperthyroidism, when there is too much thyroid hormone, your body processes speed up, and the body uses energy very quickly. And in hypothyroidism, when you don’t have enough thyroid hormone, your body processes slow down, and the body uses less energy.
That’s probably a good place to stop for this week. It’s been a while since I’ve had to write an endocrine overview, people! Next week, we’ll start getting into the meat and potatoes when it comes to thyroid imbalance- how it can affect you. Something to look forward to.
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