Hyperthyroidism |
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In this condition the level of thyroid hormone is abnormally high.
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Types and clinical signs |
There are many causes of hyperthyroidism, most of which are environmental and a small proportion of
which are genetic.
The adult-onset cases are usually caused by non-genetic factors such as inflammation of the thyroid
gland or other environmental causes.
Out of all the women with hyperthyroidism, it is important to identify those with Graves’ disease,
the characteristic clinical sign of which is exophthalmos – bulging eyeballs.
In this disease, there are antibodies against the thyroid gland. These antibodies can be detected
by a blood test.
In pregnant women, the antibodies can pass to the fetus through the placenta and affect the fetus’s
thyroid gland.
This can manifest in congenital hypothyroidism which can cause mental retardation
if left untreated.
Treatment should commence immediately after birth in order to prevent this.
The drugs that a woman with hyperthyroidism takes can also affect the fetus.
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Inheritance pattern |
In the hereditary types, this is usually multifactorial.
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Penetrance |
Partial.
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Associated features that can be demonstrated in tests performed during pregnancy |
There are usually no defects.
If the hormonal deficiency is part of a syndrome, there may be additional findings.
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What is the risk of recurrence in a subsequent pregnancy? |
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The risk that the parents of a child with hyperthyroidism will have another
affected child depends on the cause and the exact type of the disease.
The risk of recurrence is determined within genetic counseling
after reviewing all the data.
In the adult-onset types, the risk of recurrence also depends on the cause.
Usually relatives are at risk of developing this type of hyperthyroidism, which is
non-congenital, but not to the extent seen in the congenital form.
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Molecular genetic information |
The gene for the disease
In most cases, the gene is unknown.
If the exact enzyme deficiency causing the hyperthyroidism is identified, then the gene can also
be identified.
Location
Depends on the gene if the cause is genetic.
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Genetic testing |
Diagnostic testing
The disease is diagnosed by a blood test to measure the level of the thyroid hormone and the
levels of the hormones that regulate its activity: TSH and TRH.
Additional tests can also be performed, such as mapping of the thyroid gland, etc.
Carrier testing
At the present time, carrier testing is not possible in most cases.
It depends on the type of disease and whether the basic enzyme deficiency has already been identified.
Fetal testing
This is not necessary.
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Hyperthyroidism
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