Welcome back, people! Last week I introduced a new topic- the thyroid- and hopefully you remember that it’s a butterfly shaped endocrine gland that wraps around the windpipe in the forward aspect of the middle throat. It plays a major role in regulating the body’s metabolism, growth, and development by production and release of thyroid hormones, called T3 and T4, into the bloodstream. When it doesn’t work properly, it can have a huge impact on multiple systems throughout the entire body. We also talked about how all of the functions of the endocrine glands are interlinked, and that the thyroid works especially closely with the pituitary gland located in the brain. In order to make the right amount of T3 and T4, the thyroid gland needs the help of the pituitary, to “tell” it- through its own hormone called thyroid stimulating hormone, TSH- when to produce and release more or less hormones into the bloodstream. And we left off with an introduction on the two basic states that result from thyroid disease or dysfunction: hyperthyroidism, when you make too much thyroid hormone, and hypothyroidism, when you make too little.
This week, we’ll get deeper into thyroid disease and talk about the various symptoms of thyroid imbalance. But I should remind that the endocrine system and the thyroid are very dynamic and can change temporarily in response to normal natural processes other than disease. If and when the body needs more energy in certain situations- if it’s during a growth spurt, time in a very cold environment, or during pregnancy for example- the thyroid gland may temporarily produce more hormones. That increase in T3 and T4 increases the basal metabolic rate, so all of the cells in the body work harder. That causes a faster pulse and stronger heartbeat, a rise in body temperature, and activation of the nervous system and then other systems needed to accomplish whatever the situation may call for. Because the cells are working harder, they need more energy, so energy stored in the liver and body is broken down and utilized faster, and food is used up more quickly as well. When the situation has ended- say the growth phase is over, or mom has the baby- the demand is lessened, the thyroid will produce less T3 and T4, the basal metabolic rate will slow, and energy requirements will reduce to previous levels. Ultimately, the thyroid and entire endocrine system will return to their previous functional levels, ready to respond next time.
Thyroid Disease by the Numbers
Thyroid disorders are very common, and very commonly run in families, and affect more than 12 percent of Americans, or an estimated 20 million people. They can occur in anyone- men, women, teens, children, or infants- at any time, meaning they can be present at birth or may develop later. Hypothyroidism is much more common than hyperthyroidism, though the latter is easier to diagnose. About one in 20 people has some kind of thyroid disorder, which may be temporary or permanent, and up to 60 percent of people with thyroid disease are unaware of their condition. While they can occur in anyone, thyroid disease affects 5 to 8 times more women than men, so one woman in 8 will develop some type of thyroid disease at some point in her life.
When the thyroid is properly balanced, it produces and replaces just the right amount of hormones to keep your metabolism working at the proper rate. When the thyroid makes too much hormone, as in hyperthyroidism, that’s sometimes also called overactive thyroid. And the flip-side of this, when your thyroid makes too little hormone, in hypothyroidism, that’s sometimes called underactive thyroid. These conditions can be standalone or caused by other diseases and conditions that impact the way the thyroid gland works, including genetic and inherited disease.
Hyperthyroidism Causes and Conditions
There are several conditions that can cause overactive thyroid, or hyperthyroidism. The most common cause is an inherited autoimmune disorder that affects 1% of the general population, called Graves’ disease. This causes immune cells attack the thyroid gland, which responds by enlarging and secreting excess thyroid hormone. Immune cells may also go on to attack the muscles and connective tissue of the eyes, causing them to bulge, a state known as exophthalmos, and this eye condition is usually then referred to as thyroid eye disease or Graves’ eye disease.
Thyroid nodules, which are small, round, usually benign masses present within the thyroid gland tissue, can also cause thyroid overactivity. There may be a single autonomously functioning nodule or a condition called toxic multinodular goiter, where there are multiple nodules within the thyroid which produce too much hormone. As the nodules increase in size and/ or number, it can cause a large, externally obvious swelling called a goiter in the neck.
Having excess iodine in your body can also stimulate the thyroid to make more hormone than it needs, since iodine is the mineral used to make T3 and T4. Excessive iodine can be found in some cough syrups and other medications like amiodarone, a heart medication.
An inflammatory process of the thyroid called thyroiditis may also cause hyperthyroidism. The person may or may not be aware of it, as it can be painful or not felt at all. In early stages of some types of thyroiditis, the thyroid may release or leak hormones that were stored there, and this hyperthyroid state can last for a few weeks or months. If it continues, the inflammation will eventually impair the production of thyroid hormone, and this will result in hypothyroidism.
Hypothyroidism Causes and Conditions
Some of the conditions associated with underactive thyroid, or hypothyroidism, include other types of thyroiditis, where the swelling of the thyroid gland impairs hormone production. Hashimoto’s thyroiditis is the most common cause of hypothyroidism. This is an inherited autoimmune disorder whereby the body’s own immune cells attack the thyroid, causing inflammation and damage to the tissue that inhibits or halts production of hormone.
Postpartum thyroiditis is a usually temporary condition that occurs in 5% to 9% of women after childbirth, whereby the thyroid is temporarily inflamed and underactive as a result.
An iodine deficiency is a common cause of underactive thyroid, or hypothyroidism, outside of the US. When the body is deficient in iodine, it simply doesn’t have enough to produce a sufficient amount of T3 and T4 hormone. Even today, iodine deficiency affects several million people around the world.
Sometimes, the thyroid gland simply doesn’t work correctly from birth, and for obvious reasons, this can have severe implications. This condition affects about 1 in 4,000 newborns. If left untreated, the child can have both physical and mental issues in the future. Because of the potential consequences, all newborns are given a screening blood test in the hospital to check their thyroid function.
Thyroid Disease Risk Factors
The causes of thyroid dysfunction are largely unknown, but there are several factors that can place you at a higher risk of developing a thyroid disease. The first and most obvious is if you have a family history of thyroid disease, as it is commonly familial. Also, if you have had treatment for a past thyroid condition, such as a partial thyroidectomy, or cancer treatment such as radiation, you are more likely to have thyroid issues later. If you are Caucasian or Asian your risk is slightly higher. If you have prematurely graying hair, your risk for developing thyroid disease is higher. In addition, if you have certain other medical conditions like Down Syndrome, Turner syndrome, and bipolar disorder, it increases your risk. If you have autoimmune or related disorders, you are at especially increased risk: lupus, rheumatoid arthritis, pernicious anemia, celiac disease, type 1 diabetes, primary adrenal insufficiency, Sjögren’s syndrome, Addison’s disease, or vitiligo. If you take a medication that’s high in iodine, such as amiodarone, this excess iodine increases the risk for developing hyperthyroidism. And if you are over 60 years old, your risk increases. This is especially true in women, as their risk is already so much greater than men.
Thyroid Disease Symptoms
Because there are such a variety of symptoms associated with thyroid disease, many can be very similar to the signs and symptoms of other medical conditions, as well as general stages of life changes. This can make it difficult to know if your symptoms are related to a thyroid issue or something else entirely.
Symptoms of Hyperthyroidism
Because the thyroid is overactive, it speeds cellular activity and generally causes the body processes to move faster. This causes the body to use energy too quickly, so people with hyperthyroidism usually have increased appetite, and may feel weak unless they consume more food to keep up with energy demands; and even if they do, they may still lose weight unintentionally. In addition, it may cause them to have trouble sleeping and sleep disturbances, confounding the fatigue they feel. Hyperthyroidism also tends to cause increased heart rate, stronger heart beat, tremors, heat sensitivity, itching, and increased sweating. It often results in feelings of anxiety, irritability, and nervousness, and causes racing thoughts, and difficulty focusing on one task. It may cause an enlarged thyroid gland to the point of goiter, where it is visible externally, as well as problems with vision or eye irritation, including protruding or bulging eyes called exophthalmos. Women with hyperthyroidism will typically have light and irregular menstrual periods. And rarely, men with hyperthyroidism can see some breast development. Be aware that if someone experiences symptoms like irregular heart rate, dizziness, shortness of breath, and/ or loss of consciousness, that requires immediate medical attention. Hyperthyroidism can cause atrial fibrillation, which is a dangerous arrhythmia that can lead to strokes as well as congestive heart failure. This is an extreme medical emergency.
Symptoms of Hypothyroidism
When the thyroid is underactive, body processes move more slowly, and this causes people to feel extremely tired and fatigued. Because cellular processes move more slowly, less energy is required, so less stored energy is utilized. Because the metabolism is sluggish, less food is required and more is stored, so having hypothyroidism makes someone much more likely to gain weight. Mentally, people commonly experience depression, mental slowness, and forgetfulness. Physically, they commonly experience constipation, puffy face, muscle cramps, dry skin, brittle nails, dry and coarse hair, hair loss, hoarse voice, and intolerance to cold temperatures. They may experience fatigue and shortness of breath with exercise. They are likely to have joint pain, stiffness, and swelling, and even carpal tunnel syndrome. Women with hypothyroidism are likely to have frequent and heavy menstrual periods.
Kids and teens with hypothyroidism can have all of the signs above, but may also have delays in sexual maturity or puberty, growth delays and shorter stature, slow mental development, and slower development of permanent teeth.
Infants and babies with hypothyroidism may have no symptoms at all. But if symptoms do present, they can include cold hands and feet, constipation, extreme sleepiness, weak or hoarse cry, little or no growth, poor feeding habits, puffy face, stomach bloating, swollen tongue, and umbilical hernia. In addition, you may notice low muscle tone, sometimes called floppy baby, as well as persistent jaundice, which is yellowing of the skin and whites of the eyes. These symptoms require immediate medical attention.
I think we’ll pick up there next week, with complications and prognosis.
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