Thyroid hormones play an important role in growth, metabolism, and tissue differentiation in nearly all parts of the body, so it’s important to have enough (3).
When these hormones are in short supply, a wide variety of symptoms often occur, and the long-term consequences can be devastating if left untreated.
It’s always a good idea to pay attention to any symptoms you might be feeling and report them to your primary healthcare practitioner.
Other wellness practitioners should also be aware of these symptoms so they can provide proper referrals as needed.
We’ve compiled a hypothyroidism symptoms checklist below.
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Extreme tiredness or fatigue is a frequent complaint among those with hypothyroidism.
Fatigue that worsens year after year may especially be a sign of low thyroid hormone levels (compared to tiredness that remains the same) (4).
Hypothyroidism contributes to fatigue because thyroid hormones are responsible for regulating energy expenditure (5).
Having low thyroid hormone levels causes metabolism to slow down by as much as 50% as the body tries to conserve energy (8).
Nature’s best example of this effect is found in bears, who actually experience a decrease in thyroid hormone levels as they prepare for hibernation (9).
2. Cold Intolerance
If you have cold intolerance, you are more likely to feel cold when others around you feel comfortable and warm.
You may also experience pain and stiffness in your hands or feet when exposed to cold temperatures (10).
Up to 84% of patients with hypothyroidism experience cold intolerance (11).
One study actually found that mice with hypothyroidism had a body temperature that was 0.5 degrees Celsius lower than healthy mice (12).
Normally, our bodies produce heat as a result of metabolism. Adenosine triphosphate (ATP) is broken down and used for energy in the body, producing heat in the process (13).
However, hypothyroidism slows down metabolism, causing less ATP to be utilized (14). As a result, less heat is produced, leaving you feeling colder than usual.
3. Weight Gain
Unexplained weight gain is one of the most common complaints among individuals with hypothyroidism and is often the reason for deciding to see a doctor.
Weight gain tends to be more severe in people with overt hypothyroidism, compared to subclinical hypothyroidism (15).
In people producing no thyroid hormone at all, weight increases by about 10% due to increased body fat and fluid buildup (16).
When thyroid hormone levels are low, metabolism slows, and instead of burning food for energy, the body begins to store more fat (17).
Hypothyroidism also reduces the body’s ability to excrete water, leading to increased water retention.
People with severe hypothyroidism usually experience edema (water retention and swelling) due to the accumulation of water-binding carbohydrates, like hyaluronic acid (20).
Research shows that thyroid hormone inhibits the accumulation of hyaluronic acid in a dose-dependent manner (the more thyroid hormone, the less hyaluronic acid) (23).
So, in hypothyroidism, hyaluronic acid accumulates in tissues more than it normally would, causing widespread edema.
5. “Brain Fog”
Brain fog isn’t a medical term, but it’s used to describe symptoms like mental fatigue, inability to concentrate, and poor memory.
If you have subclinical (very mild) hypothyroidism, you may not notice any changes at all. In general, the lower your thyroid hormone levels are, the more likely you are to experience poor memory (26).
It’s not clear exactly how hypothyroidism leads to impaired memory, but some research suggests that it increases oxidative stress, which can cause damage to brain tissue (27).
6. Depression and Anxiety
Symptoms of depression include depressed mood, fatigue, sleep disturbances, loss of appetite, and feelings of worthlessness (32).
Anxiety, on the other hand, is characterized by excessive worrying, irrational fears, and panic attacks (33).
Scientists aren’t completely sure how hypothyroidism might lead to depression or anxiety, but it may have to do with metabolic changes in the brain triggered by low thyroid hormone levels (34).
If you often feel depressed or anxious, it’s best to see a physician or therapist who can guide you toward the best treatment for your individual needs.
7. Muscle and Joint Problems
Muscle weakness, muscle pain, joint pain, and joint swelling are common symptoms of hypothyroidism (36).
As many as 79% of hypothyroid patients suffer from myopathy (muscle weakness) (37).
Scientists aren’t sure why this happens, but it’s possible that decreased metabolism and inadequate energy supply for muscle cells leads to atrophy (wasting away) of muscle fibers (37).
Joint pain and swelling, on the other hand, may be caused by the accumulation of hyaluronic acid in connective tissue (36).
Constipation is a common problem, and people who have hypothyroidism are at a higher risk of developing the condition (39).
In one study, about 52% of hypothyroid patients reported feeling constipated (11).
Symptoms of constipation include straining to pass stool, having hard or lumpy stool, and having fewer than 3 bowel movements per week (40).
Other uncomfortable symptoms, like gas and bloating, may also occur due to the buildup of stool in the intestines (41).
In hypothyroidism, this happens because low thyroid hormone levels cause the digestive system to slow down.
The stomach begins to empty food more slowly into the small intestine, and peristalsis (intestinal contractions that propel waste) decreases (42).
Some scientists also believe that intestinal edema (fluid buildup) caused by the accumulation of hyaluronic acid in the GI tract may contribute to constipation as well (43).
9. Changes in Hair, Skin, and Nails
Thyroid hormone receptors have been found throughout the body, including in hair, skin, and nail cells (20).
When thyroid hormone levels are low, the growth of these tissues can be negatively impacted, resulting in the following symptoms.
Dry, Coarse Skin
People with hypothyroidism may notice that their skin is dry, coarse, and scaly, especially their elbows, knees, palms, and soles of their feet (20).
In one study, 90% of hypothyroid patients were found to have dry, coarse skin (11).
Thyroid hormone is responsible for maintaining balance and stimulating cell development in the skin growth cycle (20).
During hypothyroidism, the cycle of skin growth is disrupted, increasing the time that it takes to regrow new skin (20).
As a result, the old skin becomes damaged, dry, and scaly.
Our bodies are constantly producing new hair, which is regulated by a process called the hair growth cycle.
Several phases make up the hair growth cycle, including anagen (the growth phase), catagen (the regression phase), telogen (the resting phase), and exogen (hair loss) (46).
During the growth phase, hair follicles produce new hair shafts, while the regression and resting phases allow for the follicle to rest and prepare the stem cells to produce more hair during the next growth phase (46).
Some hair loss is normal and necessary so that old, damaged hair can be replaced by newer, healthier hair.
However, if you notice hair falling out in handfuls, or that your hair is so thin that your scalp is visible in several places, it might be a sign that something is wrong.
Another type of hair loss associated with hypothyroidism is the loss of the outer third of the eyebrows, causing them to appear shorter than usual (49).
Brittle, Misshapen Nails
The most common nail change seen in hypothyroidism is brittle nails, which affects between 4 and 6% of people with this condition (48).
Often, the nails are thickened and may have horizontal ridges (51).
10. Sexual and Reproductive Problems
In order to maintain normal sexual and reproductive functioning, the body needs a healthy thyroid gland.
Thyroid hormones play many roles in reproduction, but one of the most important is the regulation of sex hormone binding globulin (SBHG), a protein made by the liver that is responsible for transporting sex hormones in the blood (56, 57).
Hypothyroidism is associated with decreased SBHG, which can lead to low sex hormone levels and negatively affect sexual function in the following ways (58).
Loss of Libido
Testosterone is a sex hormone that plays many roles in sexual functioning but is especially known for its ability to increase libido (63).
Treatment with thyroid hormone usually improves sexual desire and satisfaction (60).
Erectile Dysfunction and Delayed Ejaculation
Erectile dysfunction, or the inability to achieve or maintain an erection, is common amongst men with hypothyroidism (64).
After treatment, these sexual dysfunctions can usually be reversed if thyroid hormones are restored to their normal level (68).
In one study, almost 34% of hypothyroid patients reported having abnormal menstrual cycles (70).
The two most common menstrual changes in women with low thyroid hormone levels are irregular periods and heavy bleeding (71).
Research suggests that menstrual irregularities tend to occur more often in severe hypothyroidism (71).
Because thyroid hormones interact with sexual organs, hypothyroidism can affect fertility in many ways.
However, there isn’t enough research to say what percentage of infertility is actually caused by thyroid dysfunction (77).
Fortunately, fertility can usually be improved if hypothyroidism is treated.
One study found that 76% of infertile women with previously undiagnosed hypothyroidism were able to conceive within 6 weeks to 1 year of receiving treatment (72).
11. Cardiovascular Symptoms
Thyroid hormones are important for maintaining normal cardiac functions, including heart rate, blood pressure, and cholesterol synthesis (78).
Low thyroid hormone levels can increase heart disease risk by affecting the cardiovascular system in the following ways.
Slow Heart Rate
In one study, 10% of patients with hypothyroidism had a heart rate below 60 beats per minute (normal is between 60 and 100 beats per minute) (11).
Ultimately, having a slow heart rate can mean that not enough blood is being pumped throughout the body, resulting in weakness and fatigue (84).
High Blood Pressure
Thyroid hormones help relax the smooth muscles found in blood vessels.
In hypothyroidism, less nitric oxide is released and blood vessels are more constricted (87).
As a result, the heart faces more resistance while pumping blood and blood pressure increases.
High blood pressure caused by hypothyroidism is typically reversible with thyroid hormone treatment (88).
Elevated LDL Cholesterol
If LDL can’t be broken down, it circulates in the blood and may attach to the walls of inflamed or injured blood vessels, contributing to atherosclerosis (plaque build-up and hardening of the arteries) (94).
Fortunately, treatment with thyroid hormones usually improves LDL cholesterol levels (95).
12. Enlarged Thyroid Gland
In some cases, an enlarged thyroid gland (also called a goiter) can occur with hypothyroidism, especially if it is caused by iodine deficiency (96).
Thyroid hormone is made from iodine, so when there isn’t enough iodine, the thyroid gland can’t make enough hormones (96).
In this scenario, the pituitary gland (located near the base of the brain) secretes extra thyroid-stimulating hormone (TSH) in an attempt to get the thyroid to make more hormones (96).
The thyroid gland is located in the front of the neck, and if it becomes too large it can press on the esophagus and voice box, causing difficulty swallowing, shortness of breath, and voice hoarseness (96).
Fortunately, goiter is usually painless and reverses when treated with iodine or thyroid hormone (97).
13. Hoarse Voice
One of the more unique symptoms of hypothyroidism is voice hoarseness, which is easy to overlook because it often happens very gradually over time.
There are a couple of reasons that the voice might be affected by hypothyroidism.
If you have an enlarged thyroid gland, it might compress the nerves connected to the voice box, impairing their function (96).
Or, the vocal cords themselves may become edematous (filled with fluid) as a result of the buildup of hyaluronic acid (98).
These changes can usually be reversed after 3-6 months of treatment for hypothyroidism (99).
14. Myxedema Coma
If left untreated, severe hypothyroidism may result in a life-threatening condition called myxedema coma.
Over time, chronically low thyroid hormone levels lead to hypothermia and suppressed heart function (100).
To compensate, the body decreases blood volume, restricts blood flow to the extremities, and increases blood pressure in an attempt to maintain a normal core body temperature (101).
These adaptations maintain a delicate balance that can be easily disrupted if any other health issues arise.
Eventually, multiple organs begin to fail due to inadequate blood supply, which can lead to death (104).
Although very rare, with only 0.22 cases per million people each year, myxedema crisis has a very high mortality rate (up to 60%) even when treated quickly (105).
This life-threatening condition can be easily avoided by promptly diagnosing and treating hypothyroidism.
When to See a Doctor
Because the symptoms of hypothyroidism are so general and nonspecific in nature, it’s impossible to provide a diagnosis based on symptoms alone.
In fact, one study showed that no hypothyroidism-related symptoms could effectively identify patients with hypothyroidism, and most patients with normal thyroid function had AT LEAST one symptom (106).
However, other research indicates that people who have 7 or more symptoms that have worsened over the past year are more likely to have hypothyroidism (4).
Either way, symptoms are usually an indicator that something is wrong, and if you find that you’re experiencing many of the symptoms listed above, it might be time to see a doctor.
Hypothyroidism Symptoms Checklist
To recap, some of the symptoms of hypothyroidism include:
- Cold intolerance
- Weight gain
- Brain fog
- Depression or anxiety
- Muscle and joint problems
- Dry coarse skin
- Hair loss
- Brittle nails
- Loss of libido
- Erectile dysfunction or delayed ejaculation
- Menstrual irregularities
- Reduced fertility
- Slow heart rate
- High blood pressure
- Elevated cholesterol
- Enlarged thyroid gland
- Hoarse voice
- Myxedema coma
If you experience at least 7 of these symptoms, it may be a good idea to check your thyroid hormone levels under the care of a physician.
Recommended labs include TSH, free T3, free T4, and reverse T3, plus TPO antibodies and TG antibodies to check for Hashimoto’s (autoimmune thyroid disease).
Thyroid hormones play important roles in nearly every part of the body, so when the thyroid doesn’t produce enough, the effects can be widespread.
Some of the most common signs of hypothyroidism include fatigue, weight gain, dry skin, brain fog, and constipation.
In general, the more symptoms you experience, the more likely you are to have hypothyroidism, especially if they have worsened over the past year.
However, having these symptoms doesn’t necessarily mean that you have hypothyroidism.
Having your thyroid hormone levels tested and interpreted by your healthcare practitioner is the best way to find out if you have hypothyroidism.
Don’t hesitate to get checked out, because hypothyroidism may eventually lead to more severe symptoms, such as myxedema coma, if left untreated for years.
Fortunately, treatment is readily available and typically involves taking supplemental thyroid hormone (levothyroxine) and addressing the root cause(s).
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Amy is a registered dietitian nutritionist and certified LEAP therapist. She received her Masters in Nutrition Diagnostics from Cox College and her Bachelors in Dietetics from Missouri State University. Her passion is finding ways to communicate nutrition research in an interesting and easy-to-understand way.