What Is Hypothyroidism?
Hypothyroidism is an underactive thyroid gland. An underactive thyroid can result due to either congenital or acquired causes. Thyroid hormone usually regulates brain maturation, bone growth, heart rate, and the speed at which you burn calories.
Common symptoms include cold intolerance, dry skin, decreased appetite, leg and face swelling, weight gain, constipation, and menstrual changes in women, among others .
The main treatment is hormone therapy to make up for the lack of thyroid hormone in the body.
You should visit your primary care physician. Hypothyroidism is a complex condition that is usually treated with hormone replacement therapy.
There is a wide range of symptoms that can be experienced by those with hypothyroidism, however, these are among the most common.
- Cold intolerance: One of the effects of thyroid hormone is to increase your metabolic rate, or how fast you burn calories. Burning calories produces heat in your body and contributes to body temperature regulation. Without this necessary hormone, it is harder to regulate body temperature and people with hypothyroidism will tend to feel cold in environments where others do not.
- Dry, cool skin: Thyroid hormone acts on the heart leading to increased pumping of blood to the rest of the body. With decreased thyroid hormone, the heart’s output of blood decreases, resulting in less blood reaching distant places like the hands. With less blood flow, the skin will feel cool and dry.
- Weight gain: Increased thyroid hormone results in faster metabolic rate and increased calorie burn. When thyroid hormone levels are low, the calorie burn slows down which can result in weight gain despite a decreased appetite or decreased food intake.
- Leg and face swelling: This condition is called myxedema . When the body senses that T4 and T3 thyroid hormone levels are low, it produces more TSH, as this is what stimulates T4 and T3 production. It is hypothesized that this increased TSH leads to an increase in glycosaminoglycan (GAG) deposition in the skin. While the process is molecularly complex, ultimately it just results in more water being pulled to the surface and creating the appearance of puffy legs or face.
- Constipation: Many people with hypothyroidism will experience constipation because of the effects of hormones or because of decreased food intake. The hormonal changes that occur with hypothyroidism can result in reduced GI motility; thus the movement of our GI tract to push feces forward is slowed down. As previously discussed, thyroid hormone affects how quickly you burn calories. With this decreased calorie burn, people do not require as much energy from food and therefore sometimes eat less. Less food moving through the GI tract slows down feces formation and can result in constipation.
- Decreased appetite: Thyroid hormone helps determine how quickly we use calories in our body for energy. With a slower rate of calorie burn seen in hypothyroidism, many people experience decreased appetite as they do not need to replenish these calories as quickly.
- Brittle hair and nails: While the exact reasoning behind this symptom is not known, it has been hypothesized that the decreased blood flow to distant extremities like the scalp and the hands results in poorly nourished hair and nails. The nails become brittle and break easily and hair loss is common .
Other common symptoms of hypothyroidism include the following.
- Shortness of breath with exertion: People with hypothyroidism have a decreased output of blood from their hearts. As a result, when people with hypothyroidism exert themselves, even with a simple exercise like walking, oxygenated blood is not pumped fast enough to the tissues, resulting in feelings of fatigue and shortness of breath .
- Fatigue: There are a number of reasons why hypothyroidism can cause fatigue. The most common explanation is slowing of the basic metabolic rate, or how quickly someone can burn energy. Another explanation is that many people with hypothyroidism have a decreased number of red blood cells in their bodies and are therefore considered anemic.
- Menstrual changes: The abnormal levels of T3/T4 in hypothyroidism can affect the regulatory mechanisms of hormone release from the pituitary gland. The pituitary gland is also responsible for secreting two hormones called FSH and LH that regulate the menstrual cycle. When levels of FSH and LH are affected, this can result in changes and irregularities of the menstrual cycle.
- Depressed mood: You may experience feelings of sadness or depressed mood. The exact mechanism of this change in affect is not known but is believed to be due to downstream hormonal effects.
- Infertility: Infertility that can accompany hypothyroidism may be caused by menstrual cycle irregularities or changes in the levels of a hormone called prolactin. Besides increasing the amount of thyroid hormone in the body, TRH (released from the hypothalamus) leads to increased production of prolactin, the hormone in the body that is responsible for producing milk in females. Prolactin inhibits the effects of other hormones called FSH and LH which are necessary to regulate the menstrual cycle as well as ovulation and sperm production. Hypothyroidism can, therefore, cause infertility by leading to too much prolactin.
The thyroid is a gland that is found in the neck, on top of the windpipe. It is an endocrine gland producing hormones that signal activity throughout the body. When the body needs to produce more thyroid hormone, a cascade of hormones is released. The hypothalamus, a part of our brain, releases a hormone called thyrotropin-releasing hormone (TRH), which acts on the pituitary gland in our brain. The pituitary gland then releases a hormone called thyroid stimulating hormone (TSH). TSH acts directly on the thyroid gland, stimulating it to produce hormones called T4 and T3. In other tissues of the body, T4 gets converted to T3 as this is the active form of the hormone. The effects of T3 include brain maturation, bone growth, heart rate, and speed of calorie burn.
Hypothyroidism is a condition in which there is not enough T4/T3 or, in rare cases, organs do not respond to the effects of T4/T3. There are many causes of hypothyroidism including congenital and acquired causes .
Causes of congenital hypothyroidism
The majority of cases of congenital hypothyroidism are due to absent or incomplete formation of the thyroid gland during gestation. The minority of congenital hypothyroidism cases are due to hereditary defects in the ability to produce thyroid hormone.
Causes of acquired hypothyroidism
Acquired hypothyroidism falls under the classification system of primary, secondary, or tertiary hypothyroidism.
- Primary hypothyroidism: In primary hypothyroidism there is something wrong with the thyroid gland itself. Possible etiologies of gland problems include autoimmune disease, in which the body’s own immune system destroys the gland, postpartum inflammation of the gland, a viral infection, iodine deficiency, or a side effect from medications (usually amiodarone or lithium).
- Secondary hypothyroidism: This occurs when there is a problem with the pituitary gland. A number of conditions can affect the pituitary but this ultimately results in thyroid problems if there is decreased production of TSH.
- Tertiary hypothyroidism: These are thyroid problems that result when there is a problem with the hypothalamus and it is not releasing TRH.
Who is most often affected
Hypothyroidism is five to eight times more common in women than in men, and one in eight women will develop a thyroid problem over her lifetime .
Hypothyroidism Symptom Checker
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Treatment Options and Prevention for Hypothyroidism
Hypothyroidism is diagnosed with a blood test. The TSH level is usually diagnostic of this condition. In people who have hypothyroidism, and therefore do not have enough T3/T4, the test will show elevated TSH . This means that your body is increasing this hormone to try and stimulate the thyroid to produce more T3 and T4. A physician may also test the specific levels of T3/T4 in your blood.
The standard treatment of hypothyroidism is through replacement hormone. You may be given replacement T4, also known as levothyroxine . Most people respond well to treatment and are able to reverse the symptoms associated with hypothyroidism.
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When to Seek Further Consultation for Hypothyroidism
While most of the symptoms associated with hypothyroidism are not life-threatening, they can significantly impact your quality of life. Also, none of these symptoms are uniquely specific to hypothyroidism. If you begin to experience prolonged periods of these symptoms, you should consult your doctor. At this time, your physician will likely perform a blood test for hypothyroidism to determine if this is the cause.
Questions Your Doctor May Ask to Determine Hypothyroidism
To diagnose this condition, your doctor would likely ask about the following symptoms and risk factors.
- Have you had any changes in your weight?
- Do you have trouble sleeping?
- Have you been feeling more tired than usual, lethargic or fatigued despite sleeping a normal amount?
- When was your last menstrual period?
- Any fever today or during the last week?
If you've answered yes to one or more of these questions
Hypothyroidism Symptom Checker
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- Hypothyroidism (Underactive Thyroid). National Institute of Diabetes and Digestive and Kidney Diseases. August 2016. NIDDK Link
- Gaitonde DY, Rowley KD, Sweeney LB. Hypothyroidism: An Update. Am Fam Physician. 2012 Aug 1;86(3):244-251. AAFP Link
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