Hyperthyroidism is a group of disorders characterized overproduction and secretion of thyroid hormones by the thyroid gland.
Hyperthyroidism is characterized by the activation of sympathetic nervous system . The common symptoms of hyperthyroidism include:
Older adults usually either have no symptoms, or have only subtle ones such as increased heart rate, easy fatigability and heat intolerance.
In addition to complete history, examination and base-line investigations, the following specific set of investigations are helpful in establishing the diagnosis of any thyroid disease .
In case of auto-immune thyroiditis, the most specific auto-antibody test is an ELISA (Enzyme Linked Immunosorbent Assay) test for anti-thyroid peroxidase antibody. The titres are significantly increased in case of Grave’s hyperthyroidism, but are very low or absent in case of toxic adenoma or toxic multi-nodular goiter.
Hyperthyroidism is managed by providing symptomatic relief and anti-thyroid therapy, which includes anti-thyroid drugs, radio-active iodine-131 or thyroidectomy.
The drugs commonly used are carbimazole, and propylthiouracil. Both of these drugs interfere with the oxidation of iodides and binding of iodine to tyrosine  .
Radioactive iodine (RAI)
Radioiodine destroys the thyroid cells without surgery. In this treatment, radioactive iodine is given orally which is taken up by the follicles. In the thyroid follicles, beta and gamma rays are emitted from the radioactive iodine which destroys the follicles .
Hyperthyroidism resulting from toxic multinodular goiter and toxic adenoma mostly occurs in adults and remains throughout life. Following treatment, once the person becomes euthyroid, it is generally not recommended to continue the high dose antithyroid drugs. Instead, radioactive iodine ablation is recommended.
Persistently elevated levels of thyroid hormone can cause heart complications such as left ventricular thickening. This increases the risk of sudden death in these patients. Eye problems that occur in Graves' disease usually improve after proper treatment.
Hyperthyroidism can result from several different causes that are listed below .
In the United States, the most commonly occurring form of hyperthyroidism is Graves' disease. It constitutes around 60 to 80% of the total cases. The peak occurrence is in people with ages 20 to 40.
In iodine-deficient areas, the most common type is toxic multi-nodular goiter, comprising up to 15 to 20% of total cases. It typically presents in people older than 50 years of age.
Normally, the secretion of thyroid hormones is under tight regulation by feedback mechanisms.
When the levels of thyroid hormone in the blood are low, the hypothalamus releases thyrotropin-releasing hormone (TRH) which stimulates the pituitary gland to release thyroid stimulating hormone (TSH). Thyroid stimulating hormone in turn causes the release of the thyroid hormones T3 and T4 from the thyroid gland. Increased levels of T3 and T4 decrease the production of TSH by negative feedback mechanism.
Any pathology involving the pituitary or thyroid gland or in the periphery leading to increased levels of circulating thyroid hormone can result in thyrotoxicosis. Increased levels of thyroid hormone result in a hypermetabolic state due to increased transcription of cellular proteins .
There are no current guidelines on the prevention of hyperthyroidism. Hyperthyroidism caused by Graves' disease cannot be prevented as it is genetically mediated. However, people residing in iodine deficient areas must introduce iodine in their diets to prevent the occurrence of toxic multi-nodular goiter which is most likely to occur in such areas. This might greatly affect the over-all incidence of hyperthyroidism in these areas.
Also, people with a positive family history of hyperthyroidism or those residing in iodine deficient areas should get themselves periodically checked up for early diagnosis and treatment.
Hyperthyroidism is a term reserved for disorders that result in the overproduction of the thyroid hormone by the thyroid gland. Thyrotoxicosis is a term used to describe a state of thyroid hormone excess resulting from any source. The most common cause of thyroid hormone excess is Graves disease. Toxic multinodular goiter is the second most common cause.
Hyperthyroidism refers to the condition in which the levels of thyroid hormone in the body are high. This leads to a wide range of symptoms including weight loss, increased appetite, increased sweating, intolerance to heat, anxiety and irritability. Hyperthyroidism can be treated by drugs, surgery or radiation.