Hypothyroidism (underactive thyroid) is a condition in which your thyroid gland doesn’t produce enough of certain important hormones.
Women, especially those older than age 60, are more likely to have hypothyroidism.
Symptoms
Hypothyroidism signs and symptom may include:
- Fatigue
- Increased sensitivity to cold
- Constipation
- Dry skin
- Weight gain
- Puffy face
- Hoarseness
- Muscle weakness
- Elevated blood cholesterol level
- Muscle aches, tenderness and stiffness
- Pain, stiffness or swelling in your joints
- Heavier than normal or irregular menstrual periods
- Thinning hair
- Slowed heart rate
- Depression
- Impaired memory
When hypothyroidism isn’t treated, signs and symptoms can gradually become more severe. Constant stimulation of your thyroid gland to release more hormones may lead to an enlarged thyroid (goiter). In addition, you may become more forgetful, your thought processes may slow, or you may feel depressed.
Hypothyroidism in infants
Although hypothyroidism most often affects middle-aged and older women, anyone can develop the condition, including infants. Initially, babies born without a thyroid gland or with a gland that doesn’t work properly may have few signs and symptoms. When newborns do have problems with hypothyroidism, the problems may include:
- Yellowing of the skin and whites of the eyes (jaundice). In most cases, this occurs when a baby’s liver can’t metabolize a substance called bilirubin, which normally forms when the body recycles old or damaged red blood cells.
- Frequent choking.
- A large, protruding tongue.
- A puffy appearance to the face.
As the disease progresses, infants are likely to have trouble feeding and may fail to grow and develop normally. They may also have:
- Constipation
- Poor muscle tone
- Excessive sleepiness
When hypothyroidism in infants isn’t treated, even mild cases can lead to severe physical and mental retardation.
Hypothyroidism in children and teens
In general, children and teens who develop hypothyroidism have the same signs and symptoms as adults do, but they may also experience:
- Poor growth, resulting in short stature
- Delayed development of permanent teeth
- Delayed puberty
- Poor mental development
When to see a doctor
See your doctor if you’re feeling tired for no reason or have any of the other signs or symptoms of hypothyroidism, such as dry skin, a pale, puffy face, constipation or a hoarse voice.
You’ll also need to see your doctor for periodic testing of your thyroid function if you’ve had previous thyroid surgery; treatment with radioactive iodine or anti-thyroid medications; or radiation therapy to your head, neck or upper chest. However, it may take years or even decades before any of these therapies or procedures result in hypothyroidism.
If you have high blood cholesterol, talk to your doctor about whether hypothyroidism may be a cause. And if you’re receiving hormone therapy for hypothyroidism, schedule follow-up visits as often as your doctor recommends. Initially, it’s important to make sure you’re receiving the correct dose of medicine. And over time, the dose you need may change.
Causes
When your thyroid doesn’t produce enough hormones, the balance of chemical reactions in your body can be upset. There can be a number of causes, including autoimmune disease, treatment for hyperthyroidism, radiation therapy, thyroid surgery and certain medications.
Hypothyroidism results when the thyroid gland fails to produce enough hormones. Hypothyroidism may be due to a number of factors, including:
- Autoimmune disease.
- Treatment for hyperthyroidism.
- Thyroid surgery.
- Radiation therapy.
- Medications
Less often, hypothyroidism may result from one of the following:
- Congenital disease.
- Pituitary disorder.
- Pregnancy
- Iodine deficiency.
Risk factors
Although anyone can develop hypothyroidism, you’re at an increased risk if you:
- Are a woman older than age 60
- Have an autoimmune disease
- Have a family history of thyroid disease
- Have other autoimmune diseases, such as rheumatoid arthritis or lupus, a chronic inflammatory condition
- Have been treated with radioactive iodine or anti-thyroid medications
- Received radiation to your neck or upper chest
- Have had thyroid surgery (partial thyroidectomy)
- Have been pregnant or delivered a baby within the past six months
Complications
Untreated hypothyroidism can lead to a number of health problems:
- Goiter
- Heart problems.
- Mental health issues.
- Peripheral neuropathy.
- Myxedema
- Infertility
- Birth defects.
Diagnosis
Because hypothyroidism is more prevalent in older women, some doctors recommend that older women be screened for the disorder during routine annual physical examinations. Some doctors also recommend that pregnant women or women thinking about becoming pregnant be tested for hypothyroidism.
In general, your doctor may test for an underactive thyroid if you are feeling increasingly tired, have dry skin, constipation and weight gain, or have had previous thyroid problems or a goiter.
Blood tests
Diagnosis of hypothyroidism is based on your symptoms and the results of blood tests that measure the level of TSH and sometimes the level of the thyroid hormone thyroxine. A low level of thyroxine and high level of TSH indicate an underactive thyroid. That’s because your pituitary produces more TSH in an effort to stimulate your thyroid gland into producing more thyroid hormone.
Treatment
Standard treatment for hypothyroidism involves daily use of the synthetic thyroid hormone levothyroxine. This oral medication restores adequate hormone levels, reversing the signs and symptoms of hypothyroidism.
One to two weeks after starting treatment, you’ll notice that you’re feeling less fatigued. The medication also gradually lowers cholesterol levels elevated by the disease and may reverse any weight gain. Treatment with levothyroxine is usually lifelong, but because the dosage you need may change, your doctor is likely to check your TSH level every year.
Determining proper dosage may take time
To determine the right dosage of levothyroxine initially, your doctor generally checks your level of TSH after two to three months. Excessive amounts of the hormone can cause side effects, such as:
- Increased appetite
- Insomnia
- Heart palpitations
- Shakiness
If you have coronary artery disease or severe hypothyroidism, your doctor may start treatment with a smaller amount of medication and gradually increase the dosage. Progressive hormone replacement allows your heart to adjust to the increase in metabolism.
Levothyroxine causes virtually no side effects when used in the appropriate dose and is relatively inexpensive. If you change brands, let your doctor know to ensure you’re still receiving the right dosage. Also, don’t skip doses or stop taking the drug because you’re feeling better. If you do, the symptoms of hypothyroidism will gradually return.
Proper absorption of levothyroxine
Certain medications, supplements and even some foods may affect your ability to absorb levothyroxine. Talk to your doctor if you eat large amounts of soy products or a high-fiber diet or you take other medications, such as:
- Iron supplements or multivitamins that contain iron
- Cholestyramine
- Aluminum hydroxide, which is found in some antacids
- Calcium supplements
If you have subclinical hypothyroidism, discuss treatment with your doctor. For a relatively mild increase in TSH, you probably won’t benefit from thyroid hormone therapy, and treatment could even be harmful. On the other hand, for a higher TSH level, thyroid hormones may improve your cholesterol level, the pumping ability of your heart and your energy level.