Hypothyroidism |
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This is a condition in which there is decreased or no secretion of thyroid hormone.
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Types and clinical signs |
There are many causes of hypothyroidism, some of which are environmental and some genetic.
Cases discovered in newborn babies immediately after birth are mostly genetic.
There are many hereditary types - in each there is a deficiency of a different enzyme in the
thyroid gland.
This is an endocrine gland that produces the hormone thyroxin.
It is important to diagnose this condition early and treat it immediately in order to prevent
developmental damage.
The treatment is to administer the missing thyroid hormone.
When the disease starts at an older age, it is usually secondary to inflammation of the thyroid
gland or to another environmental cause.
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Inheritance pattern |
Usually autosomal recessive.
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Penetrance |
In the hereditary types the penetrance is almost always complete.
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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 congenital hypothyroidism 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.
It is usually approximately 25%.
The risk for more distant relatives is not known.
This can also be determined within genetic counseling based on the pedigree and which
enzyme is deficient.
In the adult-onset types, the risk of recurrence also depends on the cause.
Usually relatives are at risk of developing this type of hypothyroidism, 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
If the exact enzyme deficiency causing the hypothyroidism 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
This depends on the type and whether the basic enzyme deficiency has already been identified.
Fetal testing
The condition can be diagnosed in pregnancy by an enzyme test
performed on the fetal blood (see fetal blood)
and a comparison with norms.
Such norms are only available in certain centers, and the test can be arranged through genetic
institutes.
These tests are carried out in women who have already had children with hypothyroidism.
It is possible and desirable to commence thyroxin therapy during pregnancy if it is found that the
fetus is affected.
A genetic test can be performed in pregnancy only if the basic defect has already been
identified - this occurs in a very small number of cases.
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Treating Hypothyroidism Naturally
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