Study Calls for Expanded Testing As Undiagnosed Thyroid
Disease May Affect Thousands
The largest study to date evaluating the prevalence of thyroid disease
indicates there may be more than 13 million Americans who are unaware they
have a thyroid condition even though the disease may be impacting their
short- and long-term health. This is double the previously suspected
number of undiagnosed cases in the U.S., according to data published in
the Feb. 28 issue of Archives of Internal Medicine.
As thyroid function declined, the study found, patients reported more
symptoms. But the relationship between the symptoms reported and
progressive thyroid failure is not as clear as would be expected, nor is
any single symptom a definitive indicator of thyroid failure. While there
was an increase in the likelihood of thyroid disease as the number of reported
symptoms increased, these symptoms are often vague and develop slowly so
they may go unnoticed.
Thyroid symptoms are so common and are often mistaken for signs of
aging, menopause, depression or stress, said Gay Canaris, M.D., assistant
professor in the University of Nebraska Medical Center Department of Internal
Medicine and lead author of the study. Since we cant rely upon reported
symptoms alone to detect disease, we as physicians should be conducting
thyroid testing more often.
The thyroid gland plays a vital role in overall body function during
all stages of life. Although relatively small, it produces a hormone that
influences every cell, tissue and organ in the body. The thyroid
regulates the bodys metabolism the rate at which the body produces energy
from nutrients and affects heart rate, energy and mood. Thyroid disease
can be diagnosed through a simple blood test called a TSH (thyroid stimulating
hormone).
When the thyroid gland is not working properly, it can become either
underactive (resulting in hypothyroidism) or overactive (resulting in hyperthyroidism).
Signs and symptoms of an underactive thyroid include fatigue, depression,
forgetfulness, unexplained weight gain, and menstrual irregularities.
An overactive thyroid is marked by irritability/nervousness, sleep disturbances,
unexplained weight loss, muscle weakness and vision problems. If
left untreated, thyroid disease may lead to an increased risk for heart
disease, osteoporosis and infertility.
Thyroid disease can strike anyone at any time, but is more common
in women, Dr. Canaris said.
One woman in eight will develop a thyroid disorder during her lifetime,
Dr. Canaris said. Incidence also increases with age. By age
60, more than 20 percent of American women will have a thyroid disorder.
The study, one of the largest patient populations ever evaluated, found
that of the 25,862 participants, 11.7 percent had abnormal serum TSH levels.
Evaluating incidence according to over- and underactive thyroid cases,
2,450 patients or 9.5% of the population had an underactive thyroid (hypothyroidism)
and 570 or 2.2 percent of the population had an overactive thyroid (hyperthyroidism).
The study also found that even the slightest decrease in thyroid function
may increase cholesterol levels, possibly increasing a patients risk for
cardiovascular disease. This link between the early stages of underactive
thyroid and cholesterol levels provides evidence that untreated patients
may experience serious negative health consequences.
While it has been known for decades that overt hypothyroidism contributes
to elevated cholesterol levels, this is the largest study to show that
the cholesterol levels among patients with mildly decreased thyroid function
were significantly higher than the cholesterol levels in people with normal
thyroid function.
This study was novel in that it drew a clearer connection between
mild or early stages of thyroid failure and its effect on cholesterol levels,
said Dr. E. Chester Ridgway, head of the Division of Endocrinology, University
of Colorado, and senior author of the study. It showed that as the
thyroid gland fails and less thyroid hormone is produced, blood cholesterol
levels rise. This has serious long-term consequences for the patients
health particularly in the area of cardiovascular disease.
This study clearly offers a great opportunity for preventative medicine,
especially for Americas women, Dr. Canaris said. Once diagnosed, hypothyroidism
can be treated with a synthetic hormone replacement tablet, levothyroxine
sodium, taken once a day. All we have to do is broaden the scope of current
thyroid testing, and we can help improve the quality of life for thousands
of people.
UNMC is the only public academic health science center in the state.
Through its commitment to research, education, outreach and patient care,
UNMC has established itself as one of the country’s leading centers for
cancer research and treatment, solid organ transplantation and arthritis.
During the past year, nearly $31 million in research grants and contracts
were awarded to UNMC scientists, and UNMCs funding from the National Institutes
of Health increased by 28 percent, going from $16.2 million to $20.7 million.
UNMCs educational programs are responsible for training more health professionals
practicing in Nebraska than any other institution.