The leading cause of hyperthyroidism (also known as thyrotoxicosis or 'overactive thyroid') is Graves' disease. Graves' disease represents a basic defect in the immune system, causing production of immunoglobulins (antibodies) which stimulate and attack the thyroid gland, causing growth of the gland and overproduction of thyroid hormone. Similar antibodies may also attack the tissues in the eye muscles and in the skin on the front of the lower leg.
- Graves' disease occurs in less that 1/4 of 1% of the population, but as many as 3% to 4% of asymptomatic populations have been found to have suppressed TSH levels suggestive of subclinical Graves' disease.
- Graves' disease is more prevalent among females than males.
- Graves' disease usually occurs in middle age, but also occurs in children and adolescents.
- Graves' disease is not curable, but it is a very treatable disease.
The thyroid gland
is shaped like the letter "U." The larger side parts are tucked in behind neck muscles next to the trachea
(windpipe) while the middle connecting part is closer to the skin, just below the larynx
(Adam's apple). It is like two walnuts connected at the bottom by an almond. The normal gland is barely palpable by a physician's hand, and then it is only the connecting part that can be felt. Enlargement of the gland occurs with most thyroid
ailments and is either generalized (a goiter
), nodular (bumpy) or both.
The sole function of the thyroid gland
is to make thyroid hormone. The production process involves uptake of iodine
from the bloodstream and attachment of this mineral to a protein produced within the gland. Production and release of thyroid hormone by the thyroid gland are controlled by another gland – the pituitary
. Living at the base of the brain, the pituitary gland
senses the body's need for thyroid hormone and then triggers the thyroid gland by releasing a chemical named thyroid stimulating hormone, or TSH. As you might guess, disease of the pituitary can affect function of the thyroid gland.
Thyroid hormone is the body's "governor." It controls the rate of metabolism – the speed of physiologic processes and functions. Normally everything is fine-tuned. The thyroid and its pituitary controller keep the body's machinery running at the most effective and efficient rate. But a host of environmental and genetic factors can foul the system.
The most common disease of the thyroid gland
, or under function. With too little thyroid hormone, the machinery slows and the person slows. Fatigue
, somnolence, mental sluggishness, and a desire for high room temperature are common symptoms. In advanced states the victim has thickened and boggy facial skin, a slow raspy voice, baggy eyes and a dull appearance. Thinking is slowed, and the person may appear depressed or even confused. Because an underactive thyroid gland
develops slowly, the problem often goes unrecognized by the patient, the family and even the physician. Too often the trouble is attributed to old age. Diagnosis is easy if a blood test is obtained. And treatment with a daily thyroid
hormone tablet is also easy.
Over function of the thyroid gland is less common than under function, but is not uncommon in the elderly.
Incidence; Causes and Development
Although Graves' disease
most frequently occurs in women in their middle decades (8 times more than men), it also occurs in children and in the elderly.
There are several elements contributing to the development of Graves' disease
. There is a genetic predisposition to autoimmune
disorders and infections and stress play a part. Graves' disease may have its onset after an external stressor In other instances, it may follow a viral infection or pregnancy. Many times the exact cause of Graves' disease is simply not known. It is not contagious, although it has been known to occur coincidentally between husbands and wives.
Signs and SymptomsHyperthyroidism
may manifest as an enlarged thyroid
), hair changes, erratic behavior, heart rate irregularities, tremor
, sweating, palpitations, nervousness and increased activity and eye abnormalities.
The metabolic speed-up associated with hyperthyroidism is easily diagnosed in younger patients who present with symptoms of weight loss, excess appetite, sweating, rapid pulse and tremor. In older adults these characteristic symptoms may not exist. The elderly often present with depressed mood, confusion, heart failure
, irregular pulse rate and a myriad of symptoms that do not readily suggest an acceleration of metabolism.
Diagnosis and Tests
Advances in laboratory technology now allow both underactive and overactive thyroid
conditions to be diagnosed quickly and accurately with simple blood tests. Geriatricians routinely examine a patient's thyroid gland
and order periodic blood checks – they believe it is best to detect and treat thyroid problems before significant symptoms arise. It is another reason why regular medical checkups are important for older adults.
Treatment and Prevention
Once diagnosed, treatment of hyperthyroidism
in an older person is safely accomplished by administration of radioactive iodine
. The zapped iodine molecules are taken up by the thyroid gland
and tame the overactive factory.
The selection of treatment will include factors such as age, degree of illness, and personal preferences. Generally speaking, from least invasive to most invasive, the treatments include:
- Anti-thyroid drugs that inhibit production or conversion of the active thyroid hormone (20-30% effective, often used to control mild cases)
- Radioactive iodine (I-131), which destroys part or all of the thyroid gland and renders it incapable of overproducing thyroid hormone
- Surgery, in which most of the thyroid gland is removed, renders it incapable of overproducing thyroid hormone.
The latter two treatments result in a 90-95% remission rate of the disease. In a few cases the treatments must be repeated. In all cases lifetime follow-up laboratory studies must be done, and in almost all cases lifetime replacement thyroid hormone must be taken.
Grave's disease usually responds to treatment and, after the initial period of hyperthyroidism
, is relatively easy to treat and manage.
Another common disorder of the thyroid gland
is a nodule, or lump. A physician's main concern is whether the growth is caused by cancer. Fortunately, the vast majority of nodules discovered in the elderly are harmless. "Wait and watch" is usually the best advice. If cancer of the gland is discovered, the prognosis with treatment is usually good.
The more serious complications of prolonged, untreated, or improperly treated Grave's disease include weakened heart muscle leading to heart failure
, or possible severe emotional disorders.