Hyperthyroidism (cont.)
What are the symptoms of hyperthyroidism?
Hyperthyroidism is suggested by several signs and symptoms; however, patients with mild disease usually experience
no symptoms. In patients older than 70 years, the typical signs and symptoms also
may be absent. In general, the symptoms become more obvious as the
degree of hyperthyroidism increases. The symptoms usually are related to an increase in
the metabolic rate of the body.
Common symptoms include:
In older patients,
irregular heart rhythms and heart failure can occur. In its most
severe form, untreated hyperthyroidism may result in "thyroid storm," a
condition involving high blood pressure, fever, and heart failure. Mental changes, such as confusion
and delirium, also may occur.
How is hyperthyroidism diagnosed?
Hyperthyroidism can be suspected
in patients with:
- tremors,
- excessive sweating,
- smooth velvety skin,
- fine hair,
- a
rapid heart rate, and
- an enlarged thyroid gland.
There may be puffiness around
the eyes and a characteristic stare due to the elevation of the upper eyelids.
Advanced symptoms are easily detected, but early symptoms, especially in the
elderly, may be quite inconspicuous. In all cases, a blood test is needed to
confirm the diagnosis.
The blood levels of thyroid hormones can be measured directly
and usually are elevated with hyperthyroidism. However, the main tool for
detection of hyperthyroidism is measurement of the blood TSH level. As mentioned
earlier, TSH is secreted by the pituitary gland. If an excess amount of thyroid
hormone is present, TSH is "down-regulated" and the level of TSH falls in an
attempt to reduce production of thyroid hormone. Thus, the measurement of TSH should
result in low or undetectable levels in cases of hyperthyroidism. However, there is
one exception. If the excessive amount of thyroid hormone is due to a TSH-secreting
pituitary tumor, then the levels of TSH will be abnormally high. This uncommon
disease is known as "secondary hyperthyroidism."
Although the blood tests mentioned previously can confirm the presence of excessive thyroid
hormone, they do not point to a specific cause. If there is obvious involvement
of the eyes, a diagnosis of Graves' disease is almost certain. A
combination of antibody screening (for Graves' disease) and
a thyroid scan using radioactively-labelled iodine (which concentrates in the thyroid gland)
can help diagnose the underlying thyroid disease. These investigations are chosen on
a case-by-case basis.
Next: How is hyperthyroidism treated? »
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