Pregnancy and Thyroid Disease


What is postpartum thyroiditis?

Postpartum thyroiditis is an inflammation of the thyroid gland that occurs after pregnancy. It usually occurs within a year after a woman gives birth. It affects five to ten out of every 100 women after they deliver a baby. There are usually two phases of the disease, hyperthyroidism (too much thyroid hormone) and hypothyroidism (too little thyroid hormone).

In the usual first phase, hyperthyroidism, the inflamed thyroid gland leaks stored thyroid hormone (which consists of T3 and T4) into the blood. This phase usually lasts two to four months. Too much thyroid hormone in your blood causes your metabolism to speed up.

Symptoms can include:
  • Losing weight suddenly
  • A fast heartbeat
  • Tiredness
  • Feeling nervous
  • Sweating
  • Sensitivity to heat

The inflammation can damage the thyroid, making it less able to produce thyroid hormone. This can lead to the second phase, hypothyroidism, too little thyroid hormone in the blood. This phase may last up to a year. Too little thyroid hormone in your blood slows your metabolism. Many women with hypothyroidism have a goiter, an enlarged thyroid gland that causes swelling in the front part of the neck. Other symptoms of hypothyroidism can include:

  • Unexplained weight gain or inability to lose weight
  • Feeling tired or fatigued
  • Depression
  • Dry skin and brittle nails
  • Hair loss
  • Sensitivity to cold

What are the risks of postpartum thyroiditis?

You are at greater risk of developing postpartum thyroiditis if you have an immune system disorder such as type 1 diabetes, a personal or family history of thyroid disease, or have had postpartum thyroiditis before.

For some women who develop hyperthyroidism after giving birth, the thyroid levels return to normal within a few months without going through the second phase (hypothyroidism). However, most women do experience the second phase. Of these women, about one out of five develops permanent hypothyroidism. They require life-long treatment with thyroid hormone. If left untreated, hypothyroidism can cause serious problems such as heart disease.

How is postpartum thyroiditis diagnosed?

Diagnosis depends on the phase of the disease and is based on your symptoms and laboratory test results. These tests help determine if you are in the hyper- or hypothyroid phase:

  • Level of T4 in the bloodstream.
  • Level of thyroid-stimulating hormone (TSH) in the bloodstream. This hormone is produced by the pituitary gland (located at the base of the brain), TSH tells the thyroid to produce T3 and T4.
  • Radioactive iodine uptake values. The thyroid uses iodine to make thyroid hormone. This test requires you to swallow a small dose of radioactive iodine and then measures the amount that builds up in the thyroid gland. It is not recommended for women who are nursing.
  • Levels of anti-thyroid antibodies. Inflammation of the thyroid causes your immune system to release antibodies into the bloodstream.

How is thyroiditis treated?

In the first phase (hyperthyroidism), you usually don't need treatment because symptoms are mild and brief. If your symptoms are extreme, however, your doctor might give you a beta blocker drug to slow your heart rate and lessen nervousness.

In the second phase (hypothyroidism), you will receive thyroid hormone therapy if you develop symptoms. Levothyroxine is the most commonly used thyroid hormone medication. It is a synthetic (laboratory-made) form of T4 that is the same as the T4 the thyroid gland naturally makes. After 6 to 12 months, the medication is stopped to see whether your thyroid will function normally on its own. In most cases the thyroid returns to normal, but some women develop long-term hypothyroidism and need lifelong thyroid hormone replacement therapy.

Questions to ask your doctor

  • Do my symptoms mean I might have postpartum thyroiditis?
  • What tests will I need to find out if I have postpartum thyroiditis?
  • Do I need treatment?
  • Should I be tested again? When should I have more tests?
  • I'm planning my next pregnancy. Should I have a thyroid function test?
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