The thyroid gland is located in the front of the neck, below the voice box. According to the University of Maryland Medical Center, it functions to regulate the body's metabolism and calcium balance. Hormones are secreted by the thyroid gland to stimulate tissues in the body, and the gland works in conjunction with the pituitary gland. Hyperthyroidism is a disease that develops when the body is exposed to excessive amounts of thyroid hormone; hypothyroidism as a condition in which the thyroid is under-active.
Hyperthyroidism
According to MayoClinic.com, symptoms of an overactive thyroid gland, known as hyperthyroidism, include sudden weight loss, rapid heart beat, palpitations, anxiety, sweating and increased sensitivity to heat. A goiter, or enlarged thyroid gland, may develop; this appears as a swelling at the base of the neck. Fatigue, muscle weakness and difficulty sleeping can also occur. Older adults are more likely to have subtle symptoms, or none at all, since some of the medications older people may take for high blood pressure can mask many of the hyperthyroid symptoms.
Hypothyroidism
MayoClinic.com cites symptoms of hypothyroidism such as fatigue, constipation, voice hoarseness, unexplained weight gain, achy joints, brittle fingernails and hair, and increased sensitivity to cold. The University of Maryland Medical Center explains that hypothyroidism symptoms usually appear very gradually and may be mistaken for symptoms of depression. The symptoms usually increase as the metabolism continues to slow down. A goiter may develop from the constant stimulation of the thyroid to release more hormones.
Grave's Disease
Grave's disease is the most common cause of hyperthyroidism, according to MedlinePlus. It is caused by an abnormal immune system response that causes the thyroid gland to produce excessive hormones. One common symptom of this disorder is Grave's opthalmopathy, described by MayoClinic.com as eyeballs that protrude or bulge out of the eye sockets, causing excessive tearing, double or blurred vision, and light sensitivity. Other symptoms of Grave's disease are weight loss, goiter, anxiety and hand tremors.
Hashimoto's Disease
Hashimoto's disease is the most common form of hypothyroidism, notes the University of Maryland Medical Center. It is a form of thyroiditis, or inflammation of the thyroid gland. Hashimoto's thyroiditis causes an autoimmune reaction where antibodies attack the thyroid gland. The most common symptoms include a goiter, fatigue, muscle weakness and other endocrine disorders such as diabetes. Other autoimmune disorders may also be present. The symptoms of Hashimoto's can resemble other health conditions, and the condition is often difficult to diagnose.
