先天性甲状腺功能减退.ppt

CONGENITAL HYPOTHYROIDISM
5th Year Intern- Amila Kannangara
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1
Clinical scenario..
A pregnant mother with hGoiter (enlarged thyroid gland causing a lump in the neck)
Anemia
Slow heart rate
Fluid build-up under the skin (called myxedema)
Hearing loss
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7
How to diagnose CH?
Family history should be carefully reviewed for information about similarly affected infants or family members with unexplained mental retardation.
Maternal history of a thyroid disorder and mode of treatment (whether before or during pregnancy)
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What is the chance of CH being inherited?
About 80 to 85% of the time, CH is caused when the thyroid gland does not develop at all, is misplaced, or is too small.
In about 15% of cases of CH, the thyroid gland appears normal but the amount of thyroid hormone made is reduced.  These cases are more likely to be inherited, but not always. 
Most of the hereditary types of CH are inherited in an autosomal recessive manner.
When both parents are carriers, there is a 25% chance in each pregnancy for the child to have CH. There is a 50% chance for the child to be a carrier, just like the parents. And, there is a 25% chance for the child to have two working genes.
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If a child is having inherited form of CH, is genetic testing available?
If a genetic doctor suspects an inherited form of CH, genetic testing may be available to attempt to determine the gene changes that caused the CH.  DNA testing, can be done on a blood sample.
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Can it be tested during pregnancy?
CH is not usually detectable before birth.
For those that may have an inherited form, genetic testing can confirm only a portion of the hereditary cases.
However, prenatal testing is rarely done for CH because treatment is so effective.
If a child has a hereditary form of CH, and if the gene change(s) have been found in the child, DNA testing is possible during future pregnancies.
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What other testing is available?
Blood tests to detect the