Hypothyroidism

This is when the thyroid gland doesn’t make enough hormone. It can be caused by:

• Hashimoto thyroiditis. This is an autoimmune disease. It's the main cause. It occurs when the body’s immune system attacks the thyroid gland by mistake. This damages the thyroid. So it doesn't make enough hormones.

• Too much or too little iodine in the body. The thyroid needs iodine to make hormone.

• Problems with the pituitary gland. This can lead to not enough production of thyroid hormone.

• Some medicines.

• Removing the thyroid gland during surgery.

• Pregnancy. Being pregnant can cause changes in the levels of hormones the thyroid gland makes.

Common symptoms include:

• Low energy and tiredness

• Depression

• Feeling cold

• Muscle pain

• Slowed thinking    

• Constipation

• Heavier menstrual periods with longer bleeding 

• Weight gain

• Dry and brittle skin, hair, nails

• Excessive sleepiness

Hyperthyroidism

This is when the thyroid gland makes too much hormone. It's caused by:

• Graves disease. This is an autoimmune disorder. It occurs when the body’s immune system tells the thyroid to make too much hormone by mistake.

• Small bump (nodule) in the thyroid gland. This can cause hyperthyroidism if the cells in the nodule make too much thyroid hormone. This can stop hormone production in the rest of the thyroid gland.

Common symptoms include:

• Shaking, nervousness, grouchiness

• Feeling hot

• A fast or irregular heartbeat

• Muscle weakness

• Extreme tiredness (fatigue)

• Shaking (tremors) in the hands

• More frequent bowel movements

• Shorter, lighter, or irregular menstrual periods

• Weight loss

• Hair loss

• Bulging eyes

Nodules

A thyroid nodule is an abnormal growth of thyroid cells that form a lump in the thyroid gland. In most cases, the cause isn’t known. But they may be more common in people:

• Who’ve had Hashimoto thyroiditis

• With an iodine deficiency

• Who've had treatment with radiation to the head or neck

• Who smoke

• With obesity

• With metabolic syndrome

Sometimes nodules can be felt on the outside of the neck. Most of the time, they don't cause symptoms. And they don’t affect the amount of thyroid hormone. In most cases, they're not cancer. But sometimes a nodule may be cancer. Risk factors for cancer include:

• Age

• Gender

• Family history of thyroid cancer

• Past radiation exposure

What's a goiter?

A goiter is an abnormal enlargement of the thyroid gland. When the gland enlarges, you may see or feel a swelling on your neck. A goiter can develop in someone with a normal thyroid, overactive thyroid, or underactive thyroid. The treatment will depend on the cause of the goiter.