Breastfeeding and Thyroid Problems: Diagnostic Testing & Treatments

When the thyroid is not functioning correctly, it synthroid hoarseness can impact milk production. There is also connection between thyroid disorders and autoimmune problems. You don’t want your body reacting to your growing baby as a foreign invader! Problems with the thyroid can begin before or during pregnancy, in the postpartum period, or later in life. They can also occur along with other medical conditions, which can make diagnosis and treatment more challenging. Thyroid hormones are important for your milk supply, so having a thyroid disease may interfere with its production.

When you have low thyroid levels in your body, it might be difficult for you to produce enough milk for your baby. Without enough milk supply, your baby might experience poor weight gain and low energy. ATD which are used today include propylthiouracil (PTU), carbimazole (CMZ) and methimazole (MMI) 6. PTU is about 80% protein bound, while MMI is non-protein bound and more lipid soluble 7.

Thyroid function tests

• The authors hypothesized that these levels of MMI could have a potentially harmful effect on the infant 12,13.
• Low-dose levothyroxine therapy “may be considered” in women who are using assisted reproductive techniques and test positive for thyroid peroxidase antibodies (TPOAbs), which are often present in Hashimoto’s thyroiditis.
• It was demonstrated that the amount of MMI excreted in milk was equal to MMI levels in serum, with a total of 70.0 μg MMI excreted in the milk of normal lactating subjects, 8 h following oral administration of 40 mg of MMI.
• Follow-up testing will determine if the dose needs to be further adjusted as pregnancy progresses.
• A mother with an under active thyroid needs to take medication to return her blood levels to “normal”.
• Thyroid issues often cause difficulty with milk supply and with milk removal.

Carbimazole (Neomercazole®) reaches sub-clinical levels in infants exposed to less than 30milligrammes a day through their mother’s breastmilk. If this drug is used monitoring of the infant’s thyroid function is recommended but not always essential. A mother with an overactive thyroid gland produces raised levels of levothyroxine and will experience symptoms which may include tachycardia (increased heart rate), sweating, heat intolerance and loss of body weight.

Thyroid use while Breastfeeding

Hence, a compound that is considered minimally excreted in breast milk compared to another could be harmful in certain circumstances. These additional parameters are not easily incorporated into existing in vitro risk-predicting models. New models that offer a more holistic approach of these issues are under investigation, but further studies are still required for their validation in the general population 4. Previous experimental studies assessed the excretion of ATD into human milk 10,11. In most of these studies, the mean serum PTU concentration after oral ingestion in thyrotoxic lactating women was compared with the mean total amount of PTU excreted in human milk.

• In some cases, the gland is removed surgically or by the use of radioactive iodine and levels replaced by synthetic levothyroxine.
• This issue is treated with ATDs and usually resolves within 1-3 months.
• Clinical decisions remain the responsibility of medical and breastfeeding practitioners.
• Hypothyroidism is most commonly caused by Hashimoto’s Thyroiditis, an autoimmune thyroid disease in which the immune system attacks and destroys the thyroid gland, resulting in underproduction of thyroid hormone.
• Without enough milk supply, your baby might experience poor weight gain and low energy.

A blood test can confirm the presence of antibodies (TRAb) that cause Graves’ disease, and an ultrasound can identify the presence of nodules. Although a radioactive iodine uptake & scan can distinguish between Graves’ disease and other causes of thyrotoxicosis, this procedure is not recommended during pregnancy. Thyroid dysfunction is a potential factor in infertility, possibly due to irregular menstrual cycles. The new guidelines recommend TSH testing for all women seeking treatment for infertility, with levothyroxine recommended for cases of overt hypothyroidism. Low-dose levothyroxine therapy “may be considered” in women who are using assisted reproductive techniques and test positive for thyroid peroxidase antibodies (TPOAbs), which are often present in Hashimoto’s thyroiditis. This treatment is done using radioactive iodine (I-131), but in much larger doses than used for a diagnostic scan.

Drugs and Lactation Database (LactMed®) Internet.

For women with severe thyroid illness during pregnancy, the task force recommends establishing a relationship with a neonatologist or pediatrician prior to delivery to ensure seamless care for the newborn. The guidelines recommend that women with overt or subclinical hypothyroidism, as well as those at risk for hypothyroidism, undergo TSH testing every four weeks until mid-pregnancy and at least once near 30 weeks gestation. The new guidelines (updated from a prior edition from 2011) are available free on the website of Thyroid, the official peer-reviewed journal of the ATA, published by Mary Ann Liebert, Inc., publishers. The guidelines were reviewed in advance and endorsed by a number of medical associations as well as patient groups, including the Graves’ Disease & Thyroid Foundation.

• Dealing with overactive nodules during pregnancy is challenging, as treatment with ATDs in the mother can potentially cause hypothyroidism in the fetus.
• Permanent treatment of thyrotoxicosis, such as ablation with radioactive iodine or thyroidectomy, should be considered in such cases when an euthyroid stage will need to be secured.
• The good news is that the vast majority of women with thyroid dysfunction give birth to healthy infants – and all newborns in the U.S.A. are automatically screened for thyroid dysfunction, so that any potential issues can be identified quickly.
• Levothyroxine is secreted in extremely low levels into breastmilk, if at all.
• Some moms with hyperthyroidism are also prescribed beta-blockers (such as Propranolol/Inderal) or calcium channel blockers to relieve the neurological and cardiovascular symptoms of hyperthyroidism.
• Let your obstetrician and personal care physician know if there is a family history of thyroidism.

If antibodies are elevated, the test should be repeated at weeks 18-22. Dealing with overactive nodules during pregnancy is challenging, as treatment with ATDs in the mother can potentially cause hypothyroidism in the fetus. Therefore, the task force recommends using a low dose of ATDs, with the goal of keeping the mother’s Free T4 at or slightly above the reference range.

Thyroid antibodies explained

The guidelines note that ideally, the reference range should be tailored to a specific population as well as the specific process used by the test manufacturer. For women with thyrotoxicosis due to an overactive thyroid nodule, balancing maternal and fetal thyroid function during pregnancy can be challenging; in these cases, ablative therapy (surgery or RAI) might be recommended prior to conception. Thyroid disease is diagnosed through blood tests that measure the levels of thyroid stimulating hormone (TSH) triisdothyrine (T3)/tetra-iodothyronine (thyroxine or T4).

Treatment of overt hypothyroidism is always recommended during pregnancy, and therapy is also recommended for subclinical hypothyroidism in TPOAb-positive women. The guidelines note that the recommended treatment is oral levothyroxine; combination therapy using T3 or desiccated thyroid is not recommended during pregnancy. Based on the above experimental studies regarding ATD use during lactation, it was suggested that PTU should be preferred over MMI, due to its lower concentration in milk 14. In 1989, the American Academy of Paediatrics listed PTU as a lactation-compatible treatment 15. At that time, PTU had already been considered as the first-line treatment in postpartum GH.

Breastfeeding is considered the optimal way of newborn and infant feeding by clinicians and social workers 1,2. Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.