Pregnancy and Thyroid

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Pregnancy Thyroid Testing Being Debated

http://apnews.excite.com/article/20040510/D82FS1600.html

May 10, 1:49 PM (ET)

By LAURAN NEERGAARD

WASHINGTON (AP) - Even a mildly underactive thyroid - too mild for symptoms

- may cause serious problems during pregnancy, such as premature birth or

babies born with lower IQs.

Yet whether to test every pregnant woman's blood for thyroid deficiency is

controversial.

Now specialists have come up with a compromise: a call to test women who are

at high risk for thyroid disease, before they conceive or when they are in

very early pregnancy, while pushing for major studies to settle whether even

more should be checked.

Who's at high risk? women who have thyroid disease in the family, or who

themselves have a history of thyroid problems or other autoimmune disorders

such as Type 1 diabetes, rheumatoid arthritis or lupus, says the American

Thyroid Association.

" There are a lot of women being missed currently who would fall in these

categories, " says Dr. Brent of the University of California, Los

Angeles, who helped lead an ATA-called meeting last month on the issue.

The thyroid, a bow tie-shaped gland in the neck, produces hormones that

regulate metabolism and stimulate almost every type of tissue.

An overactive thyroid increases heart rate and blood pressure, and can cause

weight loss, depression, confusion and vision problems.

Far more common is an underactive thyroid - hypothyroidism - that can slow

body functions. Symptoms are often vague: fatigue, weight gain, depression,

forgetfulness, a hoarse voice, dry skin, mood swings, intolerance to cold.

Overt thyroid disease increases the risk of heart disease, bone-thinning

osteoporosis and infertility. Fortunately, it's easily treated, and people

with symptoms are supposed to get a simple $25 blood test for diagnosis.

But some people have a mildly underactive thyroid that hasn't yet caused

symptoms - only blood testing can detect it - and that's the crux of the

pregnancy debate.

A 1999 study found that untreated hypothyroidism in pregnancy increases the

risk of having children with lowered IQs - even if the mother has no

symptoms. Thyroid hormones are important for brain development, and in the

first trimester, the fetus depends solely on the mother for them.

Now a new study shows those asymptomatic women are almost twice as likely to

have premature babies.

Researchers at the University of Texas Southwestern Medical Center tested

more than 17,000 women seeking routine prenatal care, and found 4 percent of

the 404 with asymptomatic hypothyroidism delivered prematurely - compared

with 2.5 percent of women with normal thyroids. Prematurity might explain

the lower-IQ link, says lead researcher Dr. Casey, who presented his

results at last month's thyroid meeting.

Obstetricians say there isn't enough evidence yet to warrant testing all 4

million-plus pregnant women each year to find the roughly 2.5 percent

thought to have asymptomatic hypothyroidism.

No one yet knows if treating those women reduces the risks, Casey stresses.

Because crucial brain development occurs so soon after conception,

identifying women in pregnancy may be identifying them too late to have an

impact, " he cautions.

Plus, hormone levels fluctuate during pregnancy, so there's even debate

about how to analyze women's tests.

But with potentially thousands affected, the American Thyroid Association is

pushing the government to fund such research now. Already, British

scientists have begun testing 22,000 pregnant women to see if the resulting

children of those treated for asymptomatic thyroid deficiency have better

brain function. Results will take years; checking an impact on premature

birth could be done more quickly.

Meanwhile, in addition to preconception or early pregnancy thyroid testing

for high-risk women, the ATA advises:

_Women already diagnosed with hypothyroidism need additional testing during

pregnancy, because they may need a 30- to 50-percent higher dose of thyroid

hormone.

_Pregnant women should ensure their prenatal vitamins contain iodine,

important for proper thyroid function. New research shows about a third of

prenatal vitamins contain no iodine, and few of the rest contain a full dose

Pregnant and nursing women need 220 to 290 micrograms a day, more than the

150 required for other adults.

Most Americans get enough iodine, which is commonly added to salt, but

studies suggest intake is dropping and no one knows how much pregnant women

get. Iodine also is found in seafood, dairy products and bread.

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http://apnews.excite.com/article/20040510/D82FS1600.html

EDITOR'S NOTE - n Neergaard covers health and medical issues for The

Associated Press in Washington.

On the Net:

American Thyroid Association: http://www.thyroid.org