Hyperthyroidism is a condition in which the thyroid gland (a butterfly-shaped structure present in the base of the neck just, below the Adam’s apple) is overactive and produces too much of the thyroid hormone (Hurd 2006). In this condition, the body’s metabolism rate is significantly increased due to the rise in the T3 and the T4 levels in the blood (forms of the thyroid hormone) that control several vital functions in the body (Mayo 2006). The disease can occur in acute and chronic forms.
Several functions such as fat and carbohydrate metabolism, heart rate, protein production, etc are controlled by the thyroid hormones. The pituitary gland also known as ‘master gland’ controls the release of the T3 and T4 by the thyroid gland. It is present in the hypothalamus region of the skull (Mayo 2006). The pituitary gland produces the hormone Thyroid-stimulating hormone (TSH) which controls the thyroid levels in the body through a negative feedback mechanism. If the thyroid hormone levels are low, the TSH level raises leading to increased production of thyroid hormones.
In situations in which the T3 and T4 levels are higher, the TSH levels rises in the blood (Mayo 2006). In certain tumors that affect the pituitary gland, excessive levels of TSH may be released resulting in hyperthyroidism. In Grave’s disease (an autoimmune disorder in which hyperthyroidism is present), the thyroid levels may rise due to certain antibodies prsent in the blood that encourage the thyroid gland to produce higher amounts of T3 and T4. Sometimes, the thyroid gland may get inflamed (known as ‘thyroiditis’) resulting in increased production of the thyroid hormone (Mayo 2006).
An individual who develops hyperthyroidism may develop a range of symptoms which include sudden loss of weight, increased appetite, rise in the heart rate, palpitations, arrhythmia, nervousness, anxiety attacks, tremors, irritability, menstrual problems, sweating, confusion, swelling present in the base of the neck (goiter), tiredness, sleeplessness, muscle weakness, problems in bowel movements, clammy skin, skin flushes, hair loss, gynecomastia, etc (Hurd 2006). Besides, the eyes are also affected resulting in protrusion of the eyes, hypertension, dryness of the eyeballs, sensitivity to light, osteoporosis, etc (Mayo 2006).
Hypothyroidism is a condition in which the thyroid gland does not produce enough of the thyroid hormone to make up the needs of the body (Mayo 2006). The condition more frequently occur in women than men, over that age of 50 years (Hurd 2007). Hypothyroidism can develop from a range of condition. In Hashimoto’s thyroiditis, the body’s defense mechanism produces antibodies that tend to destroy the thyroid gland tissues resulting in hypo-secretion (Mayo 2006). It may develop in association with a bacterial or a fungal infection.
Some individuals who are treated for hyperthyroidism through radio-isotope therapy, ant-thyroid agents or surgery, may develop hypothyroidism due to reduced activity of the gland (Mayo 2006). Several other treatment and diagnostic interventions such as radiotherapy involving the head and neck region, certain medications such as lithium, etc, may bring about hypothyroidism (Mayo 2006). In some cases, babies are born with a small or a missing thyroid gland and develop hypothyroidism.
The pituitary gland may produce lower amounts of TSH due to a tumor involving the gland (Mayo 2006). In general, the metabolism and activities of the body are slowed down in hypothyroidism. Some of the symptoms of hypothyroidism include sensitivity to cold, pale, hoarseness of the voice, weight gain, moon-like face, higher cholesterol levels, joint and muscle problems (pain, tenderness and swelling), depression, constipation, fatigue, weakness, abnormal menstrual cycle, drowsiness, short stature, delayed formation of the teeth, etc (Hurd 2007).
The skin appears dry, flaky and pale, and the individual may have nail abnormalities and hair loss (Hurd 2007). The teeth may take longer time to form or may not form at all (Hurd 2007). The individual may develop a goiter (swelling present in the lower part of the neck due to the enlargement of the thyroid gland). As the cholesterol levels (especially LDL or bad cholesterol) are elevated, the individual is at the risk of developing heart problems (Mayo 2006).