What is hypothyroidism?
Hypothyroidism is a chronic disease that occurs due to low levels of thyroid hormone. If hypothyroidism is not treated, long-term complications can cause debilitating disease and even death. In the U.S., autoimmune thyroid disease (Hashimoto’s thyroiditis) is the most common cause of hypothyroidism. However, globally, insufficient iodine intake is the most common cause of hypothyroidism.[1]
What are the main signs and symptoms of hypothyroidism?
Lack of thyroid hormone can result in various signs and symptoms including the following:[1]
- Fatigue and weakness
- Intolerance of cold temperature
- Decreased sweating
- Weight gain
- Depression
- Slowed heart rate
- Constipation
- Slowed movement, speech, and thinking
- Dry skin, brittle hair
- Swelling in the face and other body parts
- Goiter (enlarged thyroid)
- Joint and muscle pain
- Irregular menstrual periods and infertility in women
How is hypothyroidism diagnosed?
Since signs and symptoms of hypothyroidism are not specific, a health care professional diagnoses it with laboratory values. Most often, thyroid-stimulating hormone (TSH) levels are tested to determine if a patient has hypothyroidism. Also, free thyroxine (T4) levels are tested to determine if the patient has overt or subclinical hypothyroidism. Further testing is usually conducted to determine the cause of the hypothyroidism.[1]
What are some of the main medical treatments for hypothyroidism?
The most common treatment for hypothyroidism is the drug levothyroxine, which is a synthetic thyroid hormone (T4). To ensure that it is absorbed, levothyroxine should be taken 30-45 minutes before or at least 3 hours after a meal. Many medicines and foods can inhibit the absorption of levothyroxine (especially those containing ions like calcium and iron or substances that reduce acidity in the stomach).To ensure effectiveness, it is important to separate the intake of levothyroxine from these agents.[1][2]
Have any supplements been studied for hypothyroidism?
If hypothyroidism is caused by insufficient iodine intake, an iodine supplement is indicated. Hypothyroidism has been found to occur concurrently with deficiencies in vitamin D, selenium, magnesium, iron, zinc, and vitamin B12, however, it is unclear if supplementation will improve symptoms of hypothyroidism. Black seed has also been studied for hypothyroidism [3], while Ashwagandha has been studied for subclinical hypothyroidism.[4][5]
How could diet affect hypothyroidism?
Dietary iodine intake that is too low or too high can result in hypothyroidism, so it’s important to consume the recommended daily allowance of iodine (150 µg for non-pregnant adults).[1] Because hypothyroidism precipitates metabolic imbalances, eating a healthy, nutrient-dense diet that promotes a healthy weight is recommended to better manage the condition. Also, there is some speculation that following an anti-inflammatory diet might help reduce autoimmune damage to the thyroid in people with Hashimoto’s thyroiditis.[4]
Are there any other treatments for hypothyroidism?
What causes hypothyroidism?
The most common cause of hypothyroidism in the U.S. is Hashimoto’s thyroiditis, while in other countries it is iodine deficiency. Certain drugs and therapies can also precipitate hypothyroidism. Some examples include amiodarone, oral tyrosine kinase inhibitors, interferon, bexarotene, rifampin, phenobarbital, phenytoin, carbamazepine, interleukin-2, lithium, radioactive iodine therapy, radiation exposure, and thyroid surgery. Hypothyroidism can also be caused by disorders of the pituitary gland (secondary hypothyroidism) or hypothalamus (tertiary hypothyroidism).[1]
Examine Database: Hypothyroidism
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Frequently asked questions
Hypothyroidism is a chronic disease that occurs due to low levels of thyroid hormone. If hypothyroidism is not treated, long-term complications can cause debilitating disease and even death. In the U.S., autoimmune thyroid disease (Hashimoto’s thyroiditis) is the most common cause of hypothyroidism. However, globally, insufficient iodine intake is the most common cause of hypothyroidism.[1]
Lack of thyroid hormone can result in various signs and symptoms including the following:[1]
- Fatigue and weakness
- Intolerance of cold temperature
- Decreased sweating
- Weight gain
- Depression
- Slowed heart rate
- Constipation
- Slowed movement, speech, and thinking
- Dry skin, brittle hair
- Swelling in the face and other body parts
- Goiter (enlarged thyroid)
- Joint and muscle pain
- Irregular menstrual periods and infertility in women
Since signs and symptoms of hypothyroidism are not specific, a health care professional diagnoses it with laboratory values. Most often, thyroid-stimulating hormone (TSH) levels are tested to determine if a patient has hypothyroidism. Also, free thyroxine (T4) levels are tested to determine if the patient has overt or subclinical hypothyroidism. Further testing is usually conducted to determine the cause of the hypothyroidism.[1]
The most common treatment for hypothyroidism is the drug levothyroxine, which is a synthetic thyroid hormone (T4). To ensure that it is absorbed, levothyroxine should be taken 30-45 minutes before or at least 3 hours after a meal. Many medicines and foods can inhibit the absorption of levothyroxine (especially those containing ions like calcium and iron or substances that reduce acidity in the stomach).To ensure effectiveness, it is important to separate the intake of levothyroxine from these agents.[1][2]
If hypothyroidism is caused by insufficient iodine intake, an iodine supplement is indicated. Hypothyroidism has been found to occur concurrently with deficiencies in vitamin D, selenium, magnesium, iron, zinc, and vitamin B12, however, it is unclear if supplementation will improve symptoms of hypothyroidism. Black seed has also been studied for hypothyroidism [3], while Ashwagandha has been studied for subclinical hypothyroidism.[4][5]
Although there are a number of studies that suggest ashwagandha has thyroid-stimulating effects, the jury is still out on whether this effect is caused by supplement contamination with thyroid hormones, as opposed to ashwagandha itself.[7] There are at least three case reports where people developed thyrotoxicosis (excessively high thyroid hormone levels) from supplementing with ashwagandha.[8] There are also at least four case reports that documented a variable, modest increase in thyroid hormone levels.[9] However, there are no clinical trials testing ashwagandha in people with overt hypothyroidism. In one 8-week randomized controlled trial of 50 patients with subclinical hypothyroidism, taking 300 mg of ashwagandha root extract twice daily increased thyroxine levels by 20% while levels of thyroid-stimulating hormone (TSH) decreased by 17% compared to a starch placebo.[10] However, in another 8-week randomized controlled trial, the same dose and type of ashwagandha root extract did not affect thyroid hormones in euthyroid individuals.[11]
Dietary iodine intake that is too low or too high can result in hypothyroidism, so it’s important to consume the recommended daily allowance of iodine (150 µg for non-pregnant adults).[1] Because hypothyroidism precipitates metabolic imbalances, eating a healthy, nutrient-dense diet that promotes a healthy weight is recommended to better manage the condition. Also, there is some speculation that following an anti-inflammatory diet might help reduce autoimmune damage to the thyroid in people with Hashimoto’s thyroiditis.[4]
The most common cause of hypothyroidism in the U.S. is Hashimoto’s thyroiditis, while in other countries it is iodine deficiency. Certain drugs and therapies can also precipitate hypothyroidism. Some examples include amiodarone, oral tyrosine kinase inhibitors, interferon, bexarotene, rifampin, phenobarbital, phenytoin, carbamazepine, interleukin-2, lithium, radioactive iodine therapy, radiation exposure, and thyroid surgery. Hypothyroidism can also be caused by disorders of the pituitary gland (secondary hypothyroidism) or hypothalamus (tertiary hypothyroidism).[1]
References
Examine Database References
- Thyroid-Stimulating Hormone - Sharma AK, Basu I, Singh SEfficacy and Safety of Ashwagandha Root Extract in Subclinical Hypothyroid Patients: A Double-Blind, Randomized Placebo-Controlled TrialJ Altern Complement Med.(2018 Mar)
- Thyroid-Stimulating Hormone - Jee Hyun An, Yoon Jung Kim, Kyeong Jin Kim, Sun Hwa Kim, Nam Hoon Kim, Hee Young Kim, Nan Hee Kim, Kyung Mook Choi, Sei Hyun Baik, Dong Seop Choi, Sin Gon KimL-carnitine supplementation for the management of fatigue in patients with hypothyroidism on levothyroxine treatment: a randomized, double-blind, placebo-controlled trialEndocr J.(2016 Oct 29)