Index to this Health
Guide
Fertility
Graves' Disease and Pregnancy
Thyroxine Treatment in Pregnancy
Breast Feeding and Thyroid Disease
Infertility
Menstruation
Male Infertility
Female Infertility
Relationship Between Thyroid Disease and
Iodine
Treatment for Fibrocystic Disease of the Breast |
Health
Guides on Thyroid Disease
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Thyroid disease is
not common during pregnancy. This is because the immune system,
of which the thyroid is a part, is depressed in pregnancy in order
to protect the developing fetus. However, untreated hypothyroidism
during pregnancy may impair full and normal development to at
least a slight degree.
As a result of the
loss of this protective effect at the end of pregnancy, there
is a tendency for thyroid disease to occur in those women who
have had previous thyroid disease.
Thyroiditis is particularly
common after pregnancy. In most cases, so called "post partum
thyroiditis" tends to get better after a few weeks although recurrence
in subsequent pregnancies is highly likely.
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Fertility
Women who have been
treated for Graves' disease or Hashimoto's thyroiditis can become
pregnant, since normal fertility is restored after treatment.
Graves' disease should be treated with radioactive iodine or by
surgery before pregnancy can occur. However
it is recommended to wait six months after radioactive iodine
treatment before becoming pregnant.
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Graves'
Disease and Pregnancy
Treatment of Graves'
hyperthyroidism during pregnancy is different from that in non
pregnant women, since radioactive iodine cannot be given and surgery
should not be performed (particularly in the first and third trimesters
of the pregnancy for fear of inducing a miscarriage). Because
of the immunosuppressive effect of pregnancy, antithyroid drugs
can be given in doses lower than with non pregnant patients. Overtreatment
of the hyperthyroidism with antithyroid drugs can affect the baby's
thyroid since the drugs cross the placenta into the baby's bloodstream.
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Thyroxine
Treatment in Pregnancy
Very little thyroxine
crosses from the mother's circulation into that of the fetus -
so there is no contra-indication to taking thyroxine throughout
pregnancy. Many specialists do increase the dose slightly during
pregnancy because they feel that pregnancy increases the requirements
for thyroxine and TSH does rise.
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Breast
Feeding and Thyroid Disease
Radioactive isotopes
are secreted in milk and no isotope tests or isotope scans should
be performed on someone who is breast feeding.
Propylthiouracil can be used when
breast feeding, as only negligible amounts actually get into the
milk. Thyroxine is also secreted in the milk, but providing the
dosage in the mother is in the physiologic range, it appears to
be quite safe for the mother on thyroxine to breast feed.
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Infertility
Patients with either
hyper- or hypothyroidism tend to be infertile, although it is certainly
possible to have these diseases and still get pregnant. Once the
diseases have been treated, it is important to recommence birth
control (if desired), since fertility is restored quickly once the
patient's thyroid function is normal. In addition, both men and
women with untreated thyroid disease often have decreased sexual
desire (libido).
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Menstruation
Menstruation tends to
be increased in hypothyroidism and decreased in hyperthyroidism.
The effects of thyroid hormones on menstrual periods, ovarian function
and the endocrine system in general are complicated but important,
so that with too much or too little thyroid hormone a variety of
effects on the reproductive system can occur. Girls who become hyper-
or hypothyroid during puberty may have delayed menstrual function.
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Male
Infertility
Hyper- or hypothyroidism
is also a cause for male infertility since sperm development requires
normal thyroid hormone levels. |
Female
Infertility
One other cause
of infertility in patients with thyroid disease is the uncommon
condition of primary ovary failure. This is an autoimmune disorder,
like Graves' disease and Hashimoto's thyroiditis, caused by
proteins and white cells in the blood which attach proteins
in the patient's ovaries. This leads to shrivelling of the ovary,
failure to ovulate, premature menopause, and infertility.
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Relationship
Between Thyroid Disease and Iodine
Treatment for Fibrocystic Disease of the Breast
For unknown reasons,
the breasts, like the thyroid gland, trap iodine from the blood.
Furthermore, it is found that iodine treatment for various breast
conditions markedly improves these abnormalities. For example, iodine
is frequently given for fibrocystic disease, a lumpy nodularity
of the breast common in middle-aged women.
In normal amounts, iodine
is necessary for thyroid hormone production. Large amounts can produce
goitre and various forms of thyroid disease. Women taking iodine
for breast conditions must, therefore, be aware of the posssibility
of goitre and thyroid disease, paticularly if they previously had
thyroid disease or have a family history of thyroid abnormalities.
Doctors treating breast conditions carry out thyroid blood tests
and clinical examination every 6 months.
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A
printed version of this Health Guide is available to health care
professionals and the public. For more information call the National
Office or contact your local
chapter.
Production of
the printed version of this Health Guide was made possible through
partial funding assistance from Health Canada. The views expressed
herein are solely those of the authors and do not necessarily represent
the official policy of Health Canada. |
