It is said that the thyroid gland develops in the very early weeks of the pregnancy; it forms from tissue at the base of the tongue that travels to the area below the voice box. By about the eleventh week of pregnancy the gland can produce hormones. If the gland does not develop normally, or settles in the wrong position, it is unable to produce enough thyroid hormones (Seear, 1996). .
According to Dr. Sheila Kelton researchers still cannot yet tell why the thyroid gland sometimes fails to develop normally, it just happens (Kelton, 2009). Acquired hypothyroidism, on the other hand occurs later in childhood. In this type of hypothyroidism, some of the body's own white blood cells destroy the cells of the thyroid gland so that it no longer works efficiently. When the body's white cells attack other cells in the body as if they are germs or dangerous cells, it is called an autoimmune condition. The cause of this is not completely understood (Kelton, 2009).(Figure 2.1).
Hyperthyroidism.
When the thyroid gland becomes overactive and produces too much thyroid hormone, a person is considered to have hyperthyroidism. The most common cause of hyperthyroidism is the autoimmune condition known as Graves' disease. Graves' disease is where the antibodies cause the gland to accelerate the production of hormones (Mueller, 2003; University of Maryland, 2013). At first, you might not notice symptoms of hyperthyroidism, but over time, an increase in metabolism can cause symptoms such as: weight loss, rapid or irregular heartbeat or pounding of your heart, anxiety, irritability, trouble sleeping, trembling in your hands and fingers, increased sweating, increased sensitivity to heat, muscle weakness (see Figure 2.1). In addition to these symptoms, people with hyperthyroidism may have osteoporosis, or weak/brittle bones. In fact, hyperthyroidism might affect your bones before you have any of the other symptoms of the disorder (Mueller, 2003).
