The thyroid, located at the base of the neck, is a small endocrine gland that regulates specific types of hormones.
“The hormones produced by the thyroid control your metabolism and how your body uses energy,” said Samer Nakhle, MD, FACE, ECNU, endocrinologist at Southern Hills Hospital and Medical Center. “These hormones affect every organ — influencing your heart rate, digestion, weight, energy levels and mood, among others.”
Because it’s such a powerful force within the body, optimal thyroid function is a key component for overall health. Unfortunately, the thyroid is often misunderstood and related disorders can go unrecognized.
Thyroid hormone imbalances
When your thyroid produces too many or too few hormones, it can cause imbalances that are associated with a host of symptoms.
Hypothyroidism is the term for an underactive thyroid, one that produces too few hormones, and hyperthyroidism describes an overactive thyroid, one that produces too many hormones.
Hypothyroidism is much more common — the National Institutes of Health reports that nearly 1 in 20 Americans over the age of 12 have the condition — whereas hyperthyroidism is reported to affect only 1 in 100.
Symptoms
People who suffer from either hypothyroidism or hyperthyroidism may experience some or all of the related symptoms.
“Hypothyroidism slows (body functions) down and hyperthyroidism speeds (them) up, but the symptoms can vary,” Nakhle said. “Some patients with hypothyroidism can have a severe case, meaning they’re producing hardly any hormones or none at all, which causes more extreme symptoms. Other patients may have a mild case — they’re producing less hormones than normal, but still enough that the symptoms are minimal.”
Hyperthyroidism symptoms include:
- Weight loss
- Increased appetite
- Fast heart rate
- Anxiety/nervousness
- Irritability
- Shaking/trembling of the hands
- Sweating
- Feeling warm often/greater sensitivity to heat
- Insomnia
- Frequent bowel movements and/or diarrhea
- Muscle weakness
- Thin skin and brittle hair
- Changes in the menstrual cycle (usually shorter, lighter periods)
Hypothyroidism symptoms include:
- Weight gain and/or difficulty losing weight
- Constipation
- Fatigue
- Forgetfulness
- Depression
- Dry skin and hair/hair loss
- Slow heart rate
- Feeling cold often/greater sensitivity to cold
- Changes in the menstrual cycle (usually longer, heavier periods)
Causes
Both hypothyroidism and hyperthyroidism can be caused by autoimmune diseases that affect thyroid function. Hypothyroidism also can occur as a result of an iodine deficiency, radiation, viral infections or the surgical removal of the thyroid gland.
These conditions also may occur without any identifiable cause.
Diagnosing and treating thyroid disorders
Hypothyroidism and hyperthyroidism are generally easy to diagnose using a simple blood test to measure the amount of thyroid hormones in the blood.
There are several different treatment options for patients suffering from either condition, including hormone replacement therapy for hypothyroidism or drugs to limit thyroid function for hyperthyroidism. Hyperthyroidism also can be permanently corrected by surgically removing all, or part, of the gland.
While both conditions can usually be treated successfully, it’s rarely a one-size-fits-all equation.
“Hyperthyroidism tends to be easier to treat because you can simply remove the gland,” Nakhle said. “However, after doing so, the patient will need to use drugs to replace the thyroid hormones, which are the same drugs used for people with hypothyroidism. The hormone replacement drugs are successful about 90 percent of the time, but occasionally there are patients who don’t respond well to any of the options.”
Thyroid nodules and cancer
As people get older, they become more prone to developing nodules, or growths, on the thyroid gland.
These nodules cause the gland to enlarge, which can cause difficulty swallowing and/or breathing, and in some cases may cause visible lumps on the neck.
“Thyroid nodules are common but they’re usually easy to remove and treat,” Nakhle said. “The large majority of patients with thyroid nodules won’t have any further problems but in about 5 percent of cases, the nodules are cancerous.”
Thyroid cancer is uncommon and tends to be treatable, particularly because it’s often found in its early stages. Surgery is considered the first line of treatment — the gland is removed and hormone replacement drugs are used thereafter. Chemotherapy and/or radiation may also be used in conjunction with the surgery, but it depends on the patient and stage of the cancer.
While thyroid cancer has a high survival rate compared with most other cancers, the incidence rate is growing. According to the American Cancer Society, thyroid cancer is the most rapidly increasing cancer in the U.S., with diagnoses tripling in the past three decades.
“Thyroid cancer is the only cancer that has been increasing continually, and we don’t know why,” Nakhle said.
Women and thyroid disease
Women are affected by thyroid diseases at much higher rates than men are. The American Thyroid Association reports that women are five to eight times more likely than men to have thyroid problems and that 1 in 8 women will develop a thyroid problem during her lifetime.
Further, the American Cancer Society estimates that in 2017, there will be 56,870 new cases of thyroid cancer — of those, 42,470 will be in women.
Nakhle said women 50 and older are especially prone to hypothyroidism, whereas those in their teens and 20s are prone to hyperthyroidism.