Thyroid Issues - Dr. Neal Barnard and LaRay Seier

The endocrine system is a chemical messenger system comprising feedback loops of hormones released by internal glands of an organism directly into the circulatory system, regulating distant target organs. Endocrine glands are glands of the endocrine system that secrete their products, hormones, directly into interstitial spaces and then absorbed into blood rather than through a duct. The major glands of the endocrine system include the pineal gland, pituitary gland, pancreas, ovaries, testes, thyroid gland, parathyroid gland, hypothalamus and adrenal glands. The hypothalamus and pituitary gland are neuroendocrine organs. The thyroid gland, or simply the thyroid, is an endocrine gland in the neck, consisting of two lobes connected by an isthmus. It is found at the front of the neck, below the Adam's apple. The thyroid gland secretes three hormones, namely the two thyroid hormones (thyroxine/T4 and triiodothyronine/T3), and calcitonin. The thyroid hormones primarily influence the metabolic rate and protein synthesis, but they also have many other effects, including effects on development. A goiter is a swelling in the neck resulting from an enlarged thyroid gland. A goiter can be associated with a thyroid that is not functioning properly. Worldwide, over 90% of goiter cases are caused by iodine deficiency. A goiter, if associated with hypothyroidism or hyperthyroidism, may be present with symptoms of the underlying disorder. For hyperthyroidism, the most common symptoms are associated with adrenergic stimulation: tachycardia (increased heart rate), palpitations, nervousness, tremor, increased blood pressure and heat intolerance. Hypothyroid individuals may have weight gain despite poor appetite, cold intolerance, constipation and lethargy. However, these symptoms are often non-specific and make diagnosis difficult. Thyroid-stimulating hormone is a pituitary hormone that stimulates the thyroid gland to produce thyroxine (T4), and then triiodothyronine (T3) which stimulates the metabolism of almost every tissue in the body. TSH is secreted throughout life but particularly reaches high levels during the periods of rapid growth and development, as well as in response to stress. Hypothyroidism, also called under-active thyroid or low thyroid, is a disorder of the endocrine system in which the thyroid gland does not produce enough thyroid hormone. It can cause a number of symptoms, such as poor ability to tolerate cold, a feeling of tiredness, constipation, depression, and weight gain. Occasionally there may be swelling of the front part of the neck due to goiter. Untreated hypothyroidism during pregnancy can lead to delays in growth and intellectual development in the baby or congenital iodine deficiency syndrome. Hyperthyroidism is the condition that occurs due to excessive production of thyroid hormone by the thyroid gland. Signs and symptoms vary between people and may include irritability, muscle weakness, sleeping problems, a fast heartbeat, heat intolerance, diarrhea, enlargement of the thyroid, hand tremor, and weight loss. Graves' disease, also known as toxic diffuse goiter, is an autoimmune disease that affects the thyroid. It frequently results in and is the most common cause of hyperthyroidism. It is the cause of about 50% to 80% of the cases of hyperthyroidism in the United States. Iodine It is an essential element for life. It is required for the synthesis of the growth-regulating thyroid hormones thyroxine and triiodothyronine (T4 and T3 respectively, named after their number of iodine atoms). A deficiency of iodine leads to decreased production of T3 and T4 and a concomitant enlargement of the thyroid tissue in an attempt to obtain more iodine, causing the disease known as simple goitre. Natural sources of dietary iodine include seaweeds (such as kelp) , and plants grown on iodine-rich soil. Iodized salt is fortified with iodine in the form of sodium iodide. Dehydroepiandrosterone (DHEA), also known as androstenolone, is an endogenous steroid hormone. It is one of the most abundant circulating steroids in humans. It is one of the most abundant circulating steroids in humans, in whom it is produced in the adrenal glands, the gonads, and the brain. It functions as a metabolic intermediate in the biosynthesis of the androgen and estrogen sex steroids both in the gonads and in various other tissues.