• Consumer Health: What happens if your thyroid is too active or not active enough?

3D anatomy image with the thyroid gland highlighted

January is Thyroid Awareness Month, which makes this a good time to learn more how important it is that your thyroid functions properly.

The thyroid is a butterfly-shaped gland at the base of your neck. It produces hormones that regulate your heart rate, blood pressure, body temperature and weight. When your thyroid isn't functioning properly, whether it's too active or not active enough, all these functions are affected.


Hyperthyroidism, or overactive thyroid, occurs when your thyroid produces too much of the hormone thyroxine.

Hyperthyroidism can mimic other health problems, which can make it difficult for your health care team to diagnose. It accelerates your body's metabolism, causing a wide variety of signs and symptoms.

Symptoms of hyperthyroidism can include:

  • Unintentional weight loss
  • Fast or irregular heartbeat
  • Pounding of the heart, sometimes called heart palpitations
  • Increased hunger
  • Nervousness, anxiety and irritability
  • Tremor, usually a small trembling in the hands and fingers
  • Sweating
  • Changes in menstrual cycles
  • Increased sensitivity to heat
  • Changes in bowel patterns, especially more frequent bowel movements
  • Enlarged thyroid gland, or goiter
  • Tiredness
  • Muscle weakness
  • Sleep problems
  • Warm, moist skin
  • Thinning skin
  • Fine, brittle hair

Hyperthyroidism can lead to a number of health problems, including heart diseaseosteoporosis; vision problems; and discolored, swollen skin.

Several treatments are available for hyperthyroidism, and the best approach for you will depend on the underlying cause and severity of your condition, as well as your age, health and personal preference.

Treatment may include medications, radioiodine therapy and surgery.


With hypothyroidism, your thyroid gland doesn't produce enough of certain crucial hormones.

Hypothyroidism affects all aspects of your metabolism and influences the control of vital functions, such as body temperature and heart rate.

Hypothyroidism may not cause noticeable symptoms in the early stages. Or you may simply attribute them to getting older. But as your metabolism continues to slow, you may develop more obvious problems.

Symptoms of hypothyroidism can 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
  • Enlarged thyroid gland, or goiter

Over time, untreated hypothyroidism can cause a number of health problems, such as obesityjoint painheart disease and peripheral neuropathy.

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.

You'll likely start to feel better soon after you start treatment. The medication gradually lowers cholesterol levels elevated by the disease and may reverse any weight gain. Treatment with levothyroxine likely will be lifelong, but because the dosage you need may change, your health care team likely will check your thyroid-stimulating hormone (TSH) level every year.

Connect with others talking about thyroid function and related conditions in the Diabetes & Endocrine System support group on Mayo Clinic Connect, an online patient community moderated by Mayo Clinic.

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