Hypothyroidism – Causes, Symptoms, Treatments

What is Hypothyroidism?

Hypothyroidism, also referred to as an underactive thyroid, is a condition that develops when the thyroid gland doesn’t produce enough thyroid hormone. The thyroid gland is a butterfly-shaped gland situated at the base of your front throat.

Hypothyroidism is a fairly common condition. Nearly 5% of Americans aged 12 and over have hypothyroidism. This translates to roughly 1 in 20 people in that age group. It’s important to note that many cases are mild and may not cause noticeable symptoms.

Hypothyroidism is significantly more common in women than in men. Studies suggest Hypothyroidism is six times more common in women, affecting up to 40 in 10,000 each year compared to 6 in 10,000 men per year. The risk of developing this condition increases as you get older. So, while hypothyroidism can affect anyone, it’s more likely to develop in women and people over the age of 65.

Symptoms of Hypothyroidism

The thyroid gland’s job is to produce thyroid hormones, which act like chemical messengers throughout the body. These hormones regulate a wide range of functions, and when hypothyroidism sets in, a deficiency of these hormones disrupts these processes, leading to various symptoms. 

• Metabolism: One of the primary functions of thyroid hormones is to control your metabolic rate, which determines how efficiently your body burns calories for energy. When you have hypothyroidism, your body doesn’t produce enough thyroid hormones, causing your metabolism to slow down. This translates to your body burning fewer calories at rest, even during basic activities. This can lead to unexplained weight gain despite not necessarily eating more.
• Heart Rate: Thyroid hormones also play a crucial role in regulating your heart rate. In a healthy individual, thyroid hormones help maintain a normal heart rate. However, with hypothyroidism, the lack of these hormones can cause your heart rate to slow down. This can lead to feelings of fatigue and sluggishness.
• Digestion: The digestive system also relies on thyroid hormones to function properly. When thyroid hormone levels are low, the movement of food through your digestive tract can slow down. This can lead to constipation, bloating, and overall digestive discomfort.
• Muscle Control:  Muscle function and strength are also influenced by thyroid hormones. With hypothyroidism, you might experience muscle weakness, stiffness, and cramps. This can make everyday activities like climbing stairs or carrying groceries more challenging.
• Brain Function: Thyroid hormones are essential for normal brain development and function. When these hormones are deficient, it can affect your cognitive abilities. People with hypothyroidism may experience symptoms like memory problems, difficulty concentrating, and brain fog. They might also feel more forgetful or struggle to focus on tasks.
• Skin and Hair: Healthy hair and skin also depend on adequate thyroid hormone levels. When these hormones are low, your skin can become dry, itchy, and pale. Hair loss, especially on the scalp’s outer edges, is another common symptom of hypothyroidism. The hair may also become brittle and thin.
• Body Temperature: Thyroid hormones help regulate your body’s internal temperature. In hypothyroidism, the lack of these hormones can cause a decrease in your body temperature. This can make you feel constantly cold, even in warm environments. You might experience chills and a preference for wearing warmer clothing than usual.
• Reproductive Health: Thyroid hormones play a role in regulating the menstrual cycle in women. When these hormones are imbalanced, it can lead to irregular or heavy periods. In some cases, hypothyroidism can also contribute to fertility problems.

Causes of Hypothyroidism

The primary cause of hypothyroidism is an autoimmune disease called Hashimoto’s disease.

Also known as chronic lymphocytic thyroiditis or autoimmune thyroiditis, this condition is an autoimmune disorder that attacks the thyroid gland. In an autoimmune disease, the body’s immune system, which normally fights off germs and infections, mistakenly identifies healthy tissues as foreign and attacks them.

The thyroid gland is a butterfly-shaped gland situated at the base of your throat. It produces thyroid hormones, which influence numerous bodily functions like metabolism, heart rate, and digestion.

Normally, the thyroid gland uses iodine from your diet to make thyroid hormones. With Hashimoto’s disease, the immune system produces antibodies that target the thyroid gland. Over time, this attack by the immune system gradually damages the thyroid gland, hindering its ability to produce enough thyroid hormones. This lack of thyroid hormones leads to the various symptoms associated with hypothyroidism, such as fatigue, weight gain, and sensitivity to cold. The damage to the thyroid gland caused by Hashimoto’s disease typically happens slowly over years.

Iodine Deficiency is another culprit in causing Hypothyroidism. Iodine is a mineral essential for the thyroid gland to produce thyroid hormones. In regions with iodine deficiency, particularly in developing countries, people may not get enough iodine in their diet. This can lead to hypothyroidism, especially in pregnant women and infants who are particularly vulnerable.

Congenital Hypothyroidism refers to hypothyroidism that’s present at birth. In some cases, babies are born with a malformed thyroid gland or a thyroid gland that doesn’t function properly. Additionally, there may be issues with the parts of the brain that control the thyroid gland, leading to insufficient hormone production. Early detection and treatment of congenital hypothyroidism are crucial for a child’s development.

Certain medications can interfere with the thyroid gland’s function and contribute to hypothyroidism. Examples include lithium, a medication used for bipolar disorder, and some anti-thyroid medications used to treat hyperthyroidism (an overactive thyroid). These medications can either directly affect the thyroid gland or interfere with iodine uptake.

Thyroiditis is an inflammation of the thyroid gland. There are various types of thyroiditis, some of which can cause temporary or permanent hypothyroidism. Examples include:

• Hashimoto’s thyroiditis: Though discussed earlier as an autoimmune disease, it does cause inflammation of the thyroid.
• Postpartum thyroiditis: This can occur in women after childbirth and typically resolves on its own within a year.
• Silent thyroiditis: This is a painless inflammation that can cause temporary hyperthyroidism followed by a period of hypothyroidism before returning to normal function.

Direct damage to the thyroid gland can also cause hypothyroidism. This damage can be caused by surgery and radiation therapy. If part or all of the thyroid gland is removed during surgery to treat thyroid cancer or a goiter (enlarged thyroid gland), it can lead to hypothyroidism. Radiation treatment to the neck or chest area for cancer can damage the thyroid gland and affect its function.

Complications of Untreated Hypothyroidism

Untreated hypothyroidism can lead to a cascade of complications throughout the body if left unaddressed. A significant risk associated with untreated hypothyroidism is an increased risk of heart disease. Low thyroid hormone levels can elevate your LDL (“bad”) cholesterol and decrease HDL (“good”) cholesterol. This unhealthy cholesterol profile can lead to fatty deposits building up in your arteries, a condition known as atherosclerosis. Atherosclerosis can narrow your arteries and restrict blood flow to the heart, increasing the risk of heart attack, stroke, and other cardiovascular complications.

The lack of thyroid hormones can significantly impact your mental well-being. People with untreated hypothyroidism commonly experience symptoms like depression, anxiety, brain fog, and memory problems. These issues can significantly affect your mood, concentration, and overall quality of life.

Chronic low thyroid hormone levels can damage the nerves, especially in the hands and feet. This can cause tingling, numbness, pain, and weakness in the extremities. In severe cases, nerve damage can lead to difficulty walking and maintaining coordination.

Untreated hypothyroidism can also disrupt menstrual cycles in women, leading to irregular or heavy periods. In some cases, it can contribute to fertility problems and complications during pregnancy.

Myxedema Coma is a rare but life-threatening complication of severe, untreated hypothyroidism. It’s characterized by a significant slowing down of bodily functions, including breathing, heart rate, and body temperature. Symptoms may include extreme drowsiness, confusion, slurred speech, and seizures. Myxedema coma is a medical emergency that requires immediate treatment.

How Does Hypothyroidism Impact Pregnancy?

Hypothyroidism can significantly impact pregnancy if left untreated. During the first trimester, the fetus relies heavily on the mother’s thyroid hormone for brain development. Untreated hypothyroidism can increase the risk of miscarriage and lead to birth defects affecting the baby’s brain and nervous system.

Untreated hypothyroidism can raise the risk of complications for the mother during pregnancy, such as anemia, preeclampsia (high blood pressure during pregnancy), and placental abruption (premature detachment of the placenta).

Some women experience postpartum thyroiditis, a temporary inflammation of the thyroid gland, after giving birth. This can cause temporary hypothyroidism or hyperthyroidism (overactive thyroid).

Importance of Early Diagnosis and Management:

Fortunately, with proper diagnosis and treatment, women with hypothyroidism can have healthy pregnancies. 

Ideally, women with known hypothyroidism should consult their doctor before attempting to conceive. The doctor can adjust their medication dosage to ensure optimal thyroid hormone levels for conception and pregnancy.

Throughout pregnancy, pregnant women with hypothyroidism will need close monitoring by their doctor and a specialist. This involves frequent blood tests to check thyroid hormone levels and adjust medication as needed.

The goal is to maintain TSH (Thyroid-Stimulating Hormone) levels within the recommended range for pregnancy, which may be lower than the standard range for non-pregnant individuals. This ensures the developing baby receives sufficient thyroid hormone for proper growth. Taking prenatal vitamins with adequate folic acid is crucial for all pregnant women, but especially those with hypothyroidism.

How is Hypothyroidism Diagnosed?

Diagnosing hypothyroidism typically involves a two-pronged approach: a discussion of your symptoms and a blood test to measure thyroid hormone levels.

During your doctor’s appointment, they will likely ask you about the symptoms you’re experiencing. Common symptoms of hypothyroidism include fatigue, weight gain, sensitivity to cold, constipation, dry skin, hair loss, muscle weakness, irregular periods, difficulty concentrating, and depression. By understanding your symptoms and their duration, the doctor can get a preliminary sense of whether hypothyroidism might be a possibility.

While a discussion of symptoms provides valuable clues, a definitive diagnosis of hypothyroidism relies on blood tests. These tests measure the levels of different thyroid hormones in your bloodstream. The most common tests used for diagnosing hypothyroidism include the Thyroid-Stimulating Hormone (TSH) test. 

This is the primary test for diagnosing hypothyroidism. TSH is a hormone produced by the pituitary gland, located at the base of the brain. The pituitary gland secretes TSH to stimulate the thyroid gland to produce thyroid hormones. In an underactive thyroid gland (hypothyroidism), the TSH level usually rises because the pituitary gland is trying to “push” the thyroid to produce more hormones. A high TSH level often indicates hypothyroidism.

The Free Thyroxine (fT4) test measures the level of free thyroxine, the main thyroid hormone circulating in the bloodstream. However, in some cases, the TSH level might be slightly elevated while the fT4 level remains within the normal range. This can suggest subclinical hypothyroidism, a milder form of the condition. By analyzing both TSH and fT4 levels, doctors can get a clear picture of your thyroid function and determine if hypothyroidism is present.

How is Hypothyroidism Treated?

Hypothyroidism, while not curable, is a very treatable condition. The mainstay of treatment involves medication to replace the missing thyroid hormone.

Thyroid Hormone Replacement Medication is the primary treatment for hypothyroidism. The medication most commonly used is synthetic levothyroxine (Levothroid, Synthroid, Levoxyl, Unithroid, and others). Levothyroxine is a synthetic version of the main thyroid hormone, thyroxine (T4). By taking this medication daily, you can replace the deficient thyroid hormone and alleviate the symptoms of hypothyroidism.

The exact dosage of levothyroxine you need will be determined by your doctor based on your blood test results, your symptoms, and your overall health. After starting treatment, your doctor will likely monitor your thyroid hormone levels regularly through blood tests. This helps ensure you’re on the right dosage and your thyroid function is well-controlled. Hypothyroidism is a chronic condition, and most people will need to take thyroid hormone replacement medication for life.

While medication is the cornerstone of treatment, in some cases, your doctor might recommend additional approaches depending on the underlying cause of your hypothyroidism.

If your hypothyroidism is caused by a specific condition like iodine deficiency or certain medications, addressing that underlying cause might be necessary. For example, if your hypothyroidism stems from iodine deficiency, your doctor might recommend adding iodized salt to your diet or taking iodine supplements.

While not a replacement for medication, ensuring adequate intake of certain nutrients can support thyroid function. Nutrients like selenium and iron are essential for thyroid hormone metabolism. Your doctor can advise you on dietary modifications or suggest supplements if needed.

What Medications are Most Often Prescribed for Hypothyroidism?

The most commonly prescribed medication for hypothyroidism is synthetic levothyroxine (Levothroid, Synthroid, Levoxyl, Unithroid, and others). Levothyroxine is a synthetic version of the main thyroid hormone, thyroxine (T4). This medication replaces the deficient thyroid hormone and alleviates the symptoms of hypothyroidism.

While levothyroxine is the mainstay of treatment, in rare cases, other medications might be used:

• Liothyronine (T3): This medication is a synthetic version of triiodothyronine, another thyroid hormone. It’s used in specific situations, such as in people who have difficulty converting T4 to T3 or those with severe hypothyroidism requiring faster symptom relief.
• Liotrix (Thyrolar): This is a combination medication containing both levothyroxine (T4) and liothyronine (T3). However, due to the effectiveness of levothyroxine alone, liotrix is not as commonly prescribed.