- Hypothyroidism, wherein the thyroid gland produces an inadequate amount of thyroid hormone, is a common disorder, particularly in women of childbearing age.
- Hypothyroidism of the mother during pregnancy may result in developmental delay in the child.
- Treatment of hypothyroidism requires thyroid hormone medication.
- There may be indications to start thyroid hormone therapy in women who are borderline in thyroid function and who are either pregnant or desiring pregnancy.
- The treatment goal of hypothyroidism in pregnancy is to maintain a thyroid hormone level within high normal range.
- Pregnant women who are on thyroid hormone should have blood testing frequently during pregnancy as requirements may change.
- Early studies found that children born to mothers with severe, untreated hypothyroidism during pregnancy had lower IQ scores and impaired psychomotor (mental and motor) development. If properly controlled, often by increasing the amount of thyroid hormone, women with hypothyroidism can have healthy, unaffected babies.
Hypothyroidism Symptoms & Signs
Signs of Underactive Thyroid
The symptoms of hypothyroidism are often subtle. They can mimic the symptoms of many other conditions and are often attributed to aging. People with mild hypothyroidism may have no signs or symptoms, which generally become more obvious as the condition worsens.
Common symptoms and signs include the following:
- Modest weight gain,
- Cold intolerance,
- Excessive sleepiness,
- Dry, coarse hair,
- Hair loss…
What is hypothyroidism?
- Thyroid disease is particularly common in women of child-bearing age.
- As a result, it is no surprise that thyroid disease may complicate the course of pregnancy.
- Frequency varies among different populations and different countries. While pregnancy itself is a natural state and not a “disease,” thyroid disorders during pregnancy affect both the mother and baby.
- This article focuses specifically on hypothyroidism and pregnancy. After a general description of normal and abnormal thyroid function, recent data on long term consequences in children of mothers who had hypothyroidism during pregnancy will be reviewed.
What is the thyroid gland? Where is it located and what does it do?
The thyroid is a gland weighing about 15 grams (about half an ounce) that is located in the front of the neck just below the Adam’s apple (cricoid cartilage). The thyroid gland is responsible for the production of the body’s thyroid hormone. The thyroid responds to hormonal signals from the brain to maintain a constant level of thyroid hormone. The hormone signals are sent by specialized areas of the brain (hypothalamus and pituitary gland), eventually sending thyroid stimulating hormone (TSH) that stimulates thyroid hormone production by the thyroid gland.
Disease of the thyroid gland is extremely common. In some conditions, the thyroid may produce too much hormone. In other conditions, the thyroid may be damaged or destroyed and little, if any, thyroid hormone is produced. The main thyroid hormone is called thyroxine, or T4.
Symptoms of thyroid problems vary depending on whether there is too much or too little T4 present in the blood. With an excess of T4 (hyperthyroidism), people may complain of feeling:
- Emotionally hyper
- Hot and sweaty
Some people may have symptoms like:
If T4 levels are low (hypothyroidism) as a result of decreased production by the thyroid gland, patients often experience fatigue, lethargy, and weight gain. Constipation is common and many patients report feeling excessively cold.
How is hypothyroidism treated during pregnancy?
In many respects, the treatment of hypothyroidism in pregnant women is similar to that in nonpregnant women. A synthetic form of T4 is given to replace the missing hormone. The medication dose is regularly adjusted to maintain a steady blood level of thyroid hormone within the normal range, and the requirements for this hormone may increase during pregnancy. Therefore, it is routine practice to monitor the blood level of the thyroid stimulating hormone (TSH) during pregnancy. For more information, please read the article on hypothyroidism.
Does hypothyroidism during pregnancy hurt the fetus?
Doctors have known for years of a link between mothers with untreated severe hypothyroidism during pregnancy and developmental delay in their children after birth. This was particularly seen in mothers who came from iodine deficient areas of the country (iodine is necessary to produce thyroid hormone and is now a common component of the salt in our foods), and was observed in mothers with autoimmune thyroid disease, such as Hashimoto’s thyroiditis. Some studies have suggested that mild untreated hypothyroidism may also affect the baby’s brain development, but this relationship is less clear.
How early does the mother’s thyroid hormone affect the unborn baby?
Before birth a baby is entirely dependent on the mother for thyroid hormone until the baby’s own thyroid gland can start to function. This usually does not occur until about 12 weeks of gestation (the end of the first trimester of pregnancy). Thus, hypothyroidism of the mother may play a role early on, before many women realize they are pregnant! In fact, the babies of mothers who were hypothyroid in the first part of pregnancy, then adequately treated, exhibited slower motor development than the babies of normal mothers. However, during the latter part of pregnancy, severe, untreated hypothyroidism in the mother can also have adverse effects on the baby, as pointed out by the research described above. These children are more likely to have intellectual impairment.
A number of medical associations and organizations have made recommendations on screening for thyroid disease. Some of the recommendations are:
- All women who are planning a pregnancy should be considered for screening of thyroid disease.
- All pregnant women with a goiter (enlarged thyroid), high blood levels of thyroid antibodies, a family history of thyroid disease, or symptoms of hypothyroidism should be tested for hypothyroidism.
- In women who are borderline, or sub-clinical, hypothyroid (for example, not in the laboratory range for true hypothyroidism, but within the low normal range) and who also have positive antibodies (which may indicate an ongoing autoimmune thyroid destruction), therapy with low dose thyroid hormone at the onset of pregnancy may be beneficial.
- There is some evidence that the antibodies that may contribute to hypothyroidism can play a role in pregnancy. Some data suggest that selenium supplementation may be of benefit in women with high antibody levels at the time of preconception. This should be reviewed with your doctor.
- Women who are on thyroid hormone replacement before pregnancy should also be tested to make certain that their levels are appropriate. During pregnancy, the medication dose required may increase by up to 50%. Increases may be required as early as in the first trimester.
- Dosing is dynamic during pregnancy and should be closely monitored by regular blood testing. As the pregnancy progresses, many women require higher doses of hormone replacement.
- The dosage of thyroid hormone replacement during and after pregnancy should be carefully monitored using the blood thyroid stimulating hormone (TSH) value. The laboratory ranges for normal TSH are quite wide
- In women with hypothyroidism before conception, most go back to their pre-pregnancy dose of thyroid hormone within a few weeks to months after delivery.
The management of each woman’s situation is considered individually after consultation with her physician. The benefits of treatment extend not only to pregnant women with hypothyroidism, but also to their children.
Hyperthyroidism is a medical condition that results from an excess of thyroid hormone in the blood. Thyroid hormones control most metabolic processes in the body. In cases of hyperthyroidism, these processes are often sped up, causing symptoms of hyperthyroidism, which will be discussed later in this slide show. Thyrotoxicosis is an extreme version of hyperthyroidism that can cause severe or life-threatening symptoms, called a thyroid storm.
What Are Thyroid Hormones?
Thyroid hormones control most metabolic processes in the body. They are produced by the thyroid gland located in the anterior (front) part of the neck. These hormones affect many organs and biochemical systems in your body.
Thyroid Hormone Regulation – The Chain of Command
Complex biochemical processes in the body control the thyroid gland’s production of thyroid hormones. Two other glands – the hypothalamus and the pituitary gland – both have a biochemical effect on the thyroid. The hypothalamus (the “master gland”) releases a hormone called thyrotropin-releasing hormone (TRH), which sends a signal to the pituitary to release thyroid-stimulating hormone (TSH). In turn, TSH sends a signal to the thyroid to release thyroid hormones. A problem with any of these three glands may cause an over-production of thyroid hormone and can cause hyperthyroidism.
What Causes Hyperthyroidism?
Some common causes of hyperthyroidism that will be covered in the following slides include:
- Graves’ Disease
- Functioning adenoma (“hot nodule”) and Toxic Multinodular Goiter (TMNG)
- Excessive intake of thyroid hormones
- Abnormal secretion of TSH
- Thyroiditis (inflammation of the thyroid gland)
- Excessive iodine intake
The most common cause of hyperthyroidism is Graves’ disease. The thyroid gland itself over-produces thyroid hormone and is no longer able to respond to the pituitary and hypothalamus. Graves’ disease is five times more common in women and runs in families. Risk factors for Graves’ disease include smoking, viral illnesses, radiation to the neck, and medications. The condition is associated with an eye disease called Graves’ ophthalmopathy and skin lesions called dermopathy. Diagnosis of Graves’ disease is made by blood tests, and a nuclear medicine thyroid scan.
Functioning Adenoma and Toxic Multinodular Goiter
When the thyroid gland tissue overgrows, either in individual nodules (the functioning adenoma) or in multiple clusters (multinodular goiter), it is generally termed a “goiter.” Goiters appear as large, swollen areas in the front of the neck near the Adam’s apple. These goiters may over-produce thyroid hormone, causing symptoms of hyperthyroidism.
Excessive Use of Thyroid Hormones
Hyperthyroidism can be caused by taking too much thyroid medication. Supplemental thyroid medication is given to patients who have low thyroid hormone, or hypothyroidism. If the dose is not correct or the patient takes too much of the medication, hyperthyroidism may occur. Some people may abuse thyroid hormone medications in an attempt to lose weight. Taking thyroid hormones that the body does not need may result in hyperthyroidism.
Abnormal Secretion of TSH
Thyroid-stimulating hormone (TSH) is secreted by the pituitary gland and causes the thyroid gland to produce thyroid hormone. A tumor or problem with the pituitary gland can cause and excess of TSH to affect the thyroid, and can result in hyperthyroidism.
Thyroiditis (Inflammation of the Thyroid)
Thyroiditis is inflammation of the thyroid. It is usually caused by a viral illness. The patient may have generalized neck pain, sore throat, fever, chills, and a tender thyroid. The inflammation of the thyroid causes an increased amount of thyroid hormone to be secreted into the body, causing hyperthyroidism. After pregnancy, some women – up to 8% – may develop a condition called lymphocytic thyroiditis where white blood cells called lymphocytes accumulate in the glandular tissue. Thyroiditis can be diagnosed with blood tests and a thyroid scan.
Excessive Iodine Intake
An important component of thyroid hormone is iodine. If you consume too much iodine, the thyroid might over-produce thyroid hormone and cause hyperthyroidism. Some medications such as the anti-arrhythmic drug amiodarone (Cordarone) contain large amounts of iodine and can induce thyroid dysfunction.
Thyroid Emergency: Thyroid Storm
The rare but deadly thyroid storm requires emergency medical help. It can result from longstanding but undiagnosed hyperthyroidism. Symptoms of thyroid storm include those of uncontrolled hyperthyroidism, but tend to be much more extreme:
- Weakness and rapidly fatiguing muscles (myasthenia)
- Resting heart rate above 100 BPM (tachycardia) and other cardiovascular problems
- Overheating (hyperthermia)
- Central nervous system dysfunction
Most patients who experience thyroid storm are elderly women. If you notice these symptoms, dial 9-1-1 right away.
What Are the Symptoms of Hyperthyroidism?
When hyperthyroidism is mild, patients may not experience any symptoms. This may also occur in patients age 70 years and older.
Early symptoms may include:
- Excessive sweating
- Smooth velvety skin
- Fine hair
- Rapid heart rate
- Enlarged thyroid gland
- Puffiness around the eyes
- A characteristic ‘stare’ due to the elevation of the upper eyelids
As the disease progresses, symptoms of hyperthyroidism are all related to an increased metabolic rate and may include:
- Irregular heart rhythms and heart failure
- “Thyroid storm” – high blood pressure, fever, and heart failure
- Mental changes, such as confusion and delirium
How Is Hyperthyroidism Diagnosed?
If your doctor suspects hyperthyroidism, diagnosis is made through a blood test to measure TSH levels in your blood. To further delineate what the specific cause of the hyperthyroidism would be, tests such as antibody screenings, nuclear thyroid scans, and the use of radioactively labeled iodine can help pinpoint the cause. Hypothalamus and pituitary testing may also be necessary.
How Is Hyperthyroidism Treated?
There are several treatment options for hyperthyroidism. Treatment depends on the patient’s overall health, and whether the condition is mild or severe. Treatment may be targeted at managing the individual symptoms, use of anti-thyroid medications, radioactive iodine, or surgery in some cases.
One of the main symptoms of hyperthyroidism is a rapid heartbeat (tachycardia). The feeling of a racing heart and/or palpitations can be distressing to patients. The main treatment for this symptom is the use of a beta-blocker. Beta-blockers are a type of blood pressure medication that slows the heart rate. It does not affect the level of thyroid hormone in the blood. Examples of beta-blockers include propranolol (Inderal), atenolol (Tenormin), and metoprolol (Lopressor).
Another type of medication used to treat hyperthyroidism is antithyroid drugs. These drugs such as methimazole (Tapazole) and propylthiouracil (PTU) block the production of thyroid hormone in the gland itself. Propylthiouracil (PTU) also blocks a biochemical conversion of T4 hormone to the more active T3 hormone thereby lessening the symptoms of hyperthyroidism. A risk of taking these medications is suppression of bone marrow (agranulocytosis). Bone marrow is responsible for making white blood cells in the body. White blood cells are the body’s defense force to fight off infection. If bone marrow is suppressed it may impair the ability to fight infections. If there are signs of infection while taking antithyroid medications, contact your doctor immediately.
If the thyroid gland is overactive and producing too much thyroid hormone, treatment with radioactive iodine (ablative therapy) may be indicated. Radioactive iodine is given by mouth on a one-dose regimen. The thyroid gland needs iodine to produce thyroid hormone. The radioactive iodine is taken into the thyroid cells and destroys them. The radioactive iodine is only effective on thyroid tissue and leaves the other body tissues intact. Once the thyroid is destroyed by the radioactive iodine the patient will be on thyroid hormone replacement treatment for the rest of their lives.
The use of medications and radioactive iodine has made surgery for hyperthyroidism much less common. Surgery involves removing diseased parts of the thyroid gland through an open incision in the neck. Complications of thyroid surgery may include damage to the nerves that supply the vocal cords, infection, and damage to the parathyroid glands (four tiny glands in the thyroid tissue that regulate calcium levels in the body). If a total thyroidectomy is performed all of the thyroid tissue is removed and the patient will need to be maintained on thyroid replacement therapy for the rest of their life.
What’s Best for You?
Talk to your doctor if you think you have symptoms of hyperthyroidism. Your doctor may perform blood tests or order an ultrasound of your thyroid to diagnose the condition. Your doctor may send you to an endocrinologist (a physician who specializes in the function of the glands of the body) for further diagnostic testing or treatment. Most cases of thyroid disease and hyperthyroidism can be easily diagnosed and treated.