| FOR IMMEDIATE RELEASE Sept. 21, 2003, 9:45 a.m. EDT |
For more information, please contact the ATA at thyroid@thyroid.org. |
Antibodies Against a Hormone Receptor for TSH Can Predict
Course of Eye Disease
in Common Thyroid Condition
(PALM BEACH, FLA., Sept. 21, 2003) -The prevalence and levels of thyroid-stimulating
hormone receptor antibodies (TSHR-AB) are significantly higher in patients
with a severe course of a thyroid-associated eye disease compared to patients
with a mild course, according to a new study being presented today at
the 75th Annual Meeting of the American Thyroid Association.
Based on this knowledge, physicians can predict a good or bad course of
the eye disease, called thyroid-associated ophthalmopathy (TAO), at certain
stages. The researchers believe that they can make an accurate prediction
in about half of the patients.
TAO is an inflammatory eye disease that occurs most in cases of autoimmune
hyperthyroidism, known as Graves' disease, a common form of the overactive
thyroid condition often characterized by goiter and a slight protrusion
of the eyeballs. Half of the patients with Graves' disease show signs
of eye disease. Graves' hyperthyroidism affects 22 out of 1000 people.
The symptoms of TAO, which is also called Graves' ophthalmopathy, are
lid retraction, inflammatory lid and conjunctival swellings, forward projection
or displacement of the eyeball, impairment of eye motility with double
vision and blurred vision due to dryness of the surface of the eye, and
very rarely optic nerve compression. The severity of the eye disease goes
along with the severity of thyroid disease in many cases.
To evaluate the influence of TSH-receptor antibodies on predicting the
course of TAO, researchers in Germany identified 66 patients with TAO
and monitored their progress over two years. Their antibodies were measured
within four, eight, 12, 16, 20, and 24 months after the onset of TAO.
After two years, the patients were classified into having either a bad
or good course of the disease. The classification was done with a certain
severity and activity score, and the physician classifying the cases was
unaware of the antibody levels. The researchers note that the newest,
most sensitive assay, using the human TSH receptor, was used to measure
TSHR-AB.
Anja K. Eckstein, MD, PhD, of the University Eye Hospital in Essen, Germany,
and lead author of the study, explained that many studies have addressed
the issue of using TSHR-AB to classify TAO. However, until recently, "The
overall picture has been inconclusive due to differences in the classification
of the patients and low sensitivity of former assay systems," she
said. "A number of recent clinical and experimental studies applying
a more stringent selection criteria found evidence that TSH receptor antibodies
trigger the autoimmune process in TAO. But we are the first who have shown
that TSH receptor antibodies not only trigger but also constantly maintain
the autoimmune process in the eye."
Dr. Eckstein advises ophthalmologists to use TSH receptor antibody prevalence
and levels as an additional marker to estimate the risk for a bad or good
course of TAO. "The study provides certain levels to guide physicians
in predicting the course of the disease," she added.
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