Dec. 6, 2021

058 Thyroid Disease in Pregnancy

058 Thyroid Disease in Pregnancy

What you need to know when you have hypothyroidism or hyperthyroidism in Pregnancy

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Thyroid disease can be tricky to detect in pregnancy because many of the symptoms of thyroid disease can be mild and go undetected or are so similar to the normal side effects of pregnancy they can often be missed. In this episode, Dr. Yaakov Abdelhak, high risk perinatologist and Kristin Mallon certified nurse midwife walk us through everything we need to know about thyroid disease in pregnancy.  

What is Thyroid?


The thyroid is an endocrine gland in the neck and produces thyroid hormone. The hormone regulates your metabolism, which is your energy usage, how you absorb, and how you release it into your system. If your thyroid is working well, you wouldn’t know it because you feel fine. But if your thyroid is overactive, called “hyperthyroidism,” you might find yourself releasing too much energy into your system.

Diagnosing Thyroid Disease


Before you start diagnosing schizophrenia or bipolar disease, find out if their thyroid hormones are in the right place because they can be disguised as many psychological issues. With hypothyroidism, you might find yourself cold intolerant where everybody else seems to be comfortable, but you need a sweater or an extra jacket. You have tremendous fatigue, and you’re not active. All of these symptoms are not uncommon, especially in pregnancy. So when a woman is pregnant, it’s tough to diagnose if they have hypothyroidism.


The most common cause of hyperthyroidism is Graves disease, which stimulates your thyroid by outside antibodies that are tricking your thyroid into producing too much hormone, then you get your thyroid is overactive, and you have too much thyroid hormone in your system. The opposite is hypoactive thyroid which we call “Hashimoto’s thyroiditis.” It’s when your thyroid is underactive and is secondary to Graves disease. The thyroid gets overactive, and it turns out you get stimulated too much by the thyroid-stimulating antibodies. Then it produces an excess of thyroid hormone until it burns itself out, and now you have a thyroid that’s not working.

Understanding the Thyroid Glands


To understand the thyroid, you have to understand the most basic thyroid hormone is produced. The thyroid is a gland, but the gland does not decide how much hormone to release to the brain. The pituitary gland releases TSH or thyroid-stimulating hormone. TSH is a messenger hormone to the thyroid, which responds to TSH by generating thyroid hormones in the form of T4 and T3.


The brain or the pituitary, which is a part of the brain, produces TSH. That hormone stimulates the thyroid to produce T3 and T4. There’s another concept that’s important called thyroid-binding globulin. It’s the protein that carries T3 and T4 through the system. If there’s an excess of that binding globulin, you might have higher numbers like in pregnancy.

What happens to your thyroid hormone levels during pregnancy?


Another hormone produced by the pituitary is the Human Chorionic Gonadotropin, which is almost identical to TSH. When a person produces a tremendous amount of HCG early in pregnancy, their TSH gets suppressed.


Because TSH is so affected by HCG, we use different numbers in pregnancy in non-pregnant women. A TSH above 4.5 would indicate that she’s hypothyroid and high TSH, meaning too low thyroid. High TSH means her thyroid is underactive. Think of it as the thyroid is the horse, and the TSH is the jockey whipping the horse. So if the TSH goes up very high, it’s a sign that the horse is not moving fast enough, and if the TSH goes down too low, it’s a sign that the horse is moving fast. So if the TSH is minuscule in pregnancy, we might consider that “subclinical hyperthyroidism.” Otherwise, it’s subclinical hypothyroidism.

The Bottom Line


Hypothyroidism is much more common than hyperthyroidism in the general population. There’s a lot of underactive thyroids, not so much overactive. Even if it is overactive, it’s usually transient until it gets underactive, and then you have the underactive problem.


No matter what disease you have, there’s almost nothing. You just have to take a little Synthroid. If you’ve never had it, there’s no problem. Your body works fine. You just bypass the thyroid, you get Synthroid into your system orally, and you’re perfectly fine. If you have to choose a disease to have, don’t go with liver cancer. Go with hypothyroidism.

Common Medication for Thyroid Disease


Synthroid is the generic form of levothyroxine. Your chronologist titrates the amount of Synthroid or levothyroxine that you need. They give you some, and then they check your thyroid hormones. In pregnancy, your body’s going to metabolize thyroid hormone quicker. So even if you are on Synthroid, you need to check those levels because you might have to adjust your dose.


Methimazole is a contraindication to use in the first trimester. You need to take something because it can lead to miscarriages, preterm delivery, preeclampsia, and all the bad things. Even hypothyroidism can lead to miscarriages or conception issues.

Postpartum thyroiditis


Postpartum thyroiditis is much more common. It is inflammation of the thyroid, which eventually can turn into Hashimoto’s or hypothyroidism. So if a woman is having problems with sleeping, depression, postpartum depression, or weight gain, it’s ideal for screening the thyroid to see if it is underactive or during active thyroiditis. It can be overactive or masquerade as Graves disease or hyperthyroidism and later show up as hypothyroidism.

The Fetal Thyroid


The fetal thyroid doesn’t even come into play in the first trimester. There is no fetal thyroid action in the second. It’s important to have good normal thyroid numbers in the first trimester because you’re supplying thyroid for you and your baby. In the second trimester, the fetal thyroid gland starts to work.

Hormones and Pregnancy


When you look at TSH and other hormones in pregnancy, you look at the reflection of ATG production, especially early in pregnancy. If you grade a baby based on his TSH and T4, you’re saying, “Is HCG production high or low?” Maybe you’re saying, “Was it a great pregnancy from the get-go or not?” That has much more to do with overall performance later in life.

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