A goiter is an enlarged thyroid. This occurs when the thyroid enlarges to try and produce more hormone. A lack of iodine in the diet, which is required to make thyroxine, is one cause. During adolescence and pregnancy, the body requires more thyroid hormone and so may also enlarge during these times. In the case of enlargement due to inflammation, adolescence or pregnancy, the thyroid will return to normal after the underlying condition resolves.
Hypothyroidism is a condition resulting from under-activity of the thyroid gland.
Symptoms may include fatigue, weight gain, sensitivity to cold, hoarse voice, dry and swollen skin, dry and brittle hair, constipation and occasionally numbness and tingling of the hands and feet. The cause is unknown in most cases. Treatment consists of giving thyroid hormone and must be continued life-long. Hyperthyroidism is a condition resulting from over-activity of the thyroid gland. Symptoms include sweating, nervousness, fatigue, insomnia, sensitivity to heat, increased hunger, weight loss, diarrhea, shaky hands, and bulging eyes.