Overview of Goiter
Swelling of neck or larynx due to enlargement of thyroid gland (thyromegaly) is termed as goiter. Goiter is associated with improper functioning of thyroid gland. Thyroid gland in present at lower front of neck and produces two main hormones which are thyroxine (T-4) and triiodothyronine (T-3). These hormones play role in blood circulation, metabolism regulation. Another hormone, calcitonin helps in regulating calcium levels in blood.
Causes and Risk Factors of Goiter
One of the most common causes of goiter formation worldwide is iodine deficiency. Thyroid gland extract iodine from the blood to make thyroid hormone (TH). Deficiency of iodine prohibits gland from making enough TH and causes hypothyroidism. Decreased level of TH is sensed by pituitary gland which then secrets thyroid stimulating hormone (TSH). TSH stimulates growth of thyroid gland for more production of TH; this abnormal growth is termed as goiter. An autoimmune condition, Hashimoto’s thyroiditis in which thyroid tissue is destroyed by patient’s own immune system is another cause of goiter. Damaged gland is unable to produce adequate amount of TH due to which it is acted upon by TSH to grow in size, which may produce goiter. Another autoimmune condition, Grave’s disease is characterized by production of thyroid stimulating immunoglobulin (TSI). TSI stimulates production of more TH which causes hyperthyroidism and goiter. Single or multiple solid or fluid-filled lumps on one or both sides of thyroid gland also cause overall enlargement of gland. Cancer or inflammation (thyroiditis) of thyroid gland or other causes of overgrown gland and goiter. Cyanide poisoning is another cause if goiter, it is more prevalent in tropical countries where people eat the cyanide-rich cassava root as the staple food.
Certain factors such as lack of dietary iodine, medical history of autoimmune diseases, age above 40, being female, drugs for heart (amiodarone) and psychiatric drugs (lithobid), and radiation exposure increases the risk of developing goiter.
Signs and Symptoms of Goiter
The common signs of goiter when present can be swelling at the base of neck, tight feeling in throat, coughing, hoarseness and difficulty in breathing and swallowing. Goiter associated with increased or decreased production of thyroid hormones may show signs of underlying disorder. More common signs of hyperthyroidism are increased blood pressure, heat intolerance, increased or irregular heart beat and nervousness. Hypothyroid patients may have cold intolerance, weight gain despite poor appetite, constipation and lethargy.