Routine Thyroid Screening Should Occur During Pregnancy
Dateline: 08/19/99
August 19, 1999 -- Today's New England Journal of Medicine (NEJM) is reporting on the results of a new research study that found that untreated hypothyroidism during pregnancy
may affect a child's psychological development, and result in substantially lower I.Q. levels,
reduced motor skills, and problems with attention, language and reading.
The study found that women with untreated underactive thyroids during pregnancy are
nearly four times more likely to have children with lower I.Q. scores. The researchers
indicated that approximately 1 out of every 50 women have hypothyroidism (underactive thyroid)
during pregnancy, however other experts believe this number may actually be far larger, and that
a larger percentage of the population is undiagnosed or
undertreated.
The study showed that 19 percent of the children born to mothers with thyroid deficiency had IQ
scores of 85 or lower. This was compared to a reduced IQ level of only 5 percent of those born to
mothers without such thyroid problems. According to James E. Haddow, MD, lead study author,
Vice President and Medical Director for the Foundation for Blood Research, the range below 85
I.Q. level can mean significant impairment for children.
About Hypothyroidism and its Diagnosis
Hypothyroidism, the condition in which the thyroid is not producing sufficient hormone, can
result from thyroid surgery, radioactive iodine ablation of a hyperactive thyroid, the presence of
thyroid nodules or goiter, or most commonly due to autoimmune thyroid disease such as
Hashimoto's. Common symptoms of hypothyroidism include fatigue, weight gain, hair loss,
constipation, muscle weakness, slow heart rate, depression, dry skin, and infertility, though
dozens of symptoms are often seen in hypothyroid patients. [See: Hypothyroidism Symptoms Checklist" for a
comprehensive list of symptoms.]
Many cases of hypothyroidism can be diagnosed via a standard test known as the TSH test along
with other key thyroid levels [Thyroid Blood Test Levels
Interpretation Chart] as well as via several other methods, including the TRH test, and antibodies
testing..
Drug treatment for
hypothyroidism typically includes levothyroxine (i.e., Levoxyl, Levothroid or Synthroid), an
increasingly popular combination of levoxyl with Cytomel, or thyroid hormone combination
drugs such as Thyrolar or Armour. The NEJM published in February of 1999
a research report that says that many patients feel better on a combination drug versus the
levothyroxine (i.e., Synthroid) alone. [See the NEJM article summary
here.]
Interestingly, the researchers also found that the mothers who were subsequently discovered to be
hypothyroid had gone an average of five years before their doctors diagnosed the thyroid
disorder. A few of the women were not diagnosed until 10 years later. This is an ongoing
problem for the entire population, and some estimates find that there are as many as 13 million
people with hypothyroidism in the U.S., the majority of them women, and as many as half
undiagnosed. [See HELP! My
TSH Is "Normal" But I Think I'm Hypothyroid.]
Next Steps?
The NEJM mentioned that screening of pregnancy mothers for hypothyroidism might be
recommended. Typically, women who have undergone a procedure to remove or ablate the
thyroid, or who have a diagnosed autoimmune hypothyroidism are aware of their
hypothyroidism, and should practice particular care in preparation for pregnancy and in
management of thyroid levels during pregnancy. The greatest danger, however, is in the many
women hypothyroidism who are undiagnosed, who have normal thyroid levels with elevated
antibodies, or who have untreated subclinical hypothyroidism -- all due to chronic autoimmune
thyroiditis (Hashimoto's Thyroiditis).
The prevalence of this problem suggests that all women intending to get pregnant should have a
thyroid function test prior to becoming pregnant, and during the early part of the first trimester,
and again in trimesters two and three, in order to ensure that thyroid hormone levels are sufficient
for both mother and fetal health.
Another issue is concerns over iodine intake. In the New England Journal editorial accompanying the
main article, Dr. Robert
D. Utiger says "Despite the presumption that hypothyroidism in most pregnant women is caused
by chronic autoimmune thyroiditis, which cannot be prevented, the difference among countries
suggests another possible explanation -- iodine deficiency, which is preventable. . . It is likely
that both chronic autoimmune thyroiditis and iodine deficiency contribute to the occurrence of
hypothyroidism in pregnant women in many countries." This points to the key implication that
prenatal vitamins should ensure adequate iodine intake.
Before about 12 weeks' gestation, when a fetus' thyroid gland becomes active, the mother is the
sole source of thyroid hormones for development of the fetus. Insufficient thyroid hormone in the
mother at that stage may be a particular danger to mother and baby, and may in fact increase risk
of miscarriage. This is why it is particularly important for women with diagnosed thyroid disease
to work with a doctor who understands management of hypothyroidism, particularly in the early
stages and first trimester, when thyroid hormone dosages sometimes need to be increased up to
40% in order to meet the demands of pregnancy. In addition, there are some particular theories
regarding how high -- even within the normal range -- it is safe for a hypothyroid mother to be,
and these are discussed in Thyroid Disease and
Pregnancy.
I also report on the latest in-depth news in thyroid disease and treatment options in my free
Thyroid Disease email report, called Sticking Out Our Necks. This information-packed
free monthly report is filled with the latest conventional and alternative news from around the
world related to thyroid disease, related symptoms and conditions, and the drugs, treatments,
alternative remedies, and other information you need to feel well. Send me an email at mshomon@pop.dn.net with the subject "Subscribe newsletter" to sign up.
"The children whose scores are in this
range may face life-long developmental challenges. It might be possible to prevent these
problems through the early diagnosis and treatment of thyroid disease in their mothers."
The study found that the 62 children whose mothers were hypothyroid during pregnancy
performed less well on all the various intelligence and IQ tests used for measurement. The
children of the 48 women who were not treated for thyroid disease during the pregnancy had an
average I.Q. score that was 7 points lower than the children in the control group, with 19 percent
scoring 85 or less.
There are new developments happening all the time in the world of health, and even in
conventional and alternative thyroid disease treatment. These developments are covered here at
the site. To make sure you don't miss any new information that might help, I put out a regular
About.com Thyroid Newsletter that provides free updates on new features and new information
here at the website. It's the best way to keep up with what's new here at the About.com Thyroid
Website. You can subscribe at the About.com Thyroid
Site Newsletter Signup page or right here,
And finally, I also have a new book coming out later this year, Living Well With
Hypothyroidism: What Your Doctors Don't Tell You...That You Need to Know, from
HarperCollins/Avon's WholeCare Line. The book provides in-the-trenches, practical
patient-oriented advice on how to find the right doctor to diagnose and treat various forms of
hypothyroidism, the drugs for hypothyroidism you and your doctor may not know about, fertility
and successful pregnancy with hypothyroidism, alternative therapies for hypothyroidism and its
symptoms and side effects, combatting weight gain and successful weight loss, depression, and
much more. It's a complete manual of living well for anyone with hypothyroidism, whether due
to congenital hypothyroidism, thyroid surgery, radiation, or autoimmune disease. If you'd like
advance notification of the book, send me an email at mshomon@pop.dn.net with the subject "Notify Book" and I'll be sure you receive
personal notification from me when the book is coming out.
