Hypothyroidism is a condition also known as underactive thyroid disease.

The thyroid is a small, butterfly-shaped gland located at the base of the neck, just below the Adam's apple. Hormones produced by the thyroid gland have an enormous impact on health, affecting all aspects of metabolism — from the rate at which your heart beats to how quickly calories are burned.

As long as your thyroid releases the proper amounts of these hormones, your system functions normally. But sometimes your thyroid doesn't produce enough hormones, upsetting the balance of chemical reactions in your body.

Hypothyroidism seldom causes symptoms in the early stages, but over time, untreated hypothyroidism can cause a number of health problems, such as obesity, joint pain, infertility and heart disease.

Accurate thyroid function tests are available to diagnose hypothyroidism.