When your thyroid functions normally, it produces hormones that regulate the growth and function of many different internal organs, including the liver, kidneys, and spleen. When things go awry the thyroid may be responsible for an overproduction or underproduction of hormones, affecting many important systems. In other cases, thyroid nodules may form; these are usually benign, but occasionally become cancerous. Any of these common thyroid disorders can cause a goiter (an enlarged thyroid).
An abundance of thyroid hormone causes hyperthyroidism, a condition in which the metabolism speeds up. This results in anxiety and irritability and is characterized by muscle weakness, fatigue, trembling hands, weight loss, vision problems, and sensitivity to heat. A common culprit is Grave’s disease, a disorder in which the immune system “attacks” the thyroid gland by producing antibodies that cause excess hormone production.
Too little thyroid hormone, on the other hand, results in hypothyroidism. This disorder causes the metabolism to slow down, leading to tiredness, weakness, dry skin, brittle nails, constipation, memory problems, depression, unusually heavy or irregular menstrual periods, weight gain, and intolerance to cold. It is often caused by Hashimoto’s disease, another condition in which the immune system attacks the thyroid gland, only in this case too little hormone is produced.
Thyroid nodules are small lumps, usually noncancerous, that grow on the thyroid gland. As they get bigger they can cause pain and swelling, and may lead to hoarseness and difficulty swallowing or breathing. In rare cases, these nodules become malignant.