The thyroid is often overlooked when talking about fertility, despite being a key organ for hormone production. We usually talk about hormones that are produced in the ovaries – -such as oestrogen and progesterone – when investigating fertility but the thyroid plays a much more crucial role than we might believe. So where is the link between thyroid and female fertility: keep reading to find out more about this butterfly-shaped organ.
What is the thyroid?
The thyroid is a small organ, nestled in the neck, just behind the Adam’s apple. It plays a crucial role in the endocrine (aka hormonal) system, controlling our body’s metabolism with the help of some hormones. The thyroid is controlled by the pituitary gland which sits in our brain, sending messages to the thyroid by means of the thyroid stimulating hormone (TSH) to excrete something called triiodohyronine and thyroxine, also called T3 and T4 respectively. What the thyroid essentially does it control how fast or slow our metabolism is, depending on how much T3 or T4 it produces.
What is thyroid dysfunction?
What is Hyporthyroidism?
The most common thyroid disease in the world is an underactive thyroid gland also known as hypothyroidism. If you are hypothyroid, your thyroid just is not producing enough thyroxine. You might also experience symptoms such as tiredness, weight gain and feeling cold all the time. It can present vaguely and some people might just brush it off as feeling run down or exhausted. ou can also have an overactive thyroid which is medically known as hyperthyroidism.
What is Hyperthyroidism?
An overactive thyroid means the thyroid gland is producing too much thyroxine and everything in your body is essentially speeding up. You might feel hot all the time, losing weight unintentionally or just feel generally shaky/anxious. A blood test will show a very low TSH as the pituitary does not need to stimulate the thyroid gland to produce thyroxine as it is doing it on its own.
The link between thyroid dysfunction and fertility?
The thyroid gland is essential in making two very important reproductive hormones called the follicle-stimulating hormone and luteinising hormone.
The follicle-stimulating hormone, as illustrated by the name, stimulates the egg follicles in the ovary to grow before releasing the egg. The luteinising hormone has another role in the female reproductive system, regulating our menstrual cycle and ovulatory phase. So if you think of it, any imbalance in the thyroid will result in an imbalance in our reproductive hormones and can result in major fertility problems.
The thyroid gland is not only important for getting pregnant, it is also important for the maintenance of pregnancy.Once pregnant, the job of the thyroid hormones continues as it plays a number of different roles in the development of the baby. The mothers thyroid hormones are passed to the baby through the placenta and have an effect on the baby’s brain development early on in the pregnancy. If thyroid hormones are either too high or low, it can increase the risk of pregnancy associated complications such as miscarriage.
What hormones should I get tested?
If you want to check the health of your thyroid, you can ask your doctor (usually your GP or fertility doctor) to conduct a thyroid function test. It is a blood test measuring the levels of FSH and T4 in your circulation and has a high accuracy in diagnosing thyroid related diseases. It is not common for the blood test to measure T3 levels as it is not as abundant as T4.
For an underactive thyroid, a blood test will show a high level of TSH and low levels of T4 while an overactive thyroid will show a low level of TSH and high T4.
On some occasions, if your doctor suspects, they might conduct a thyroid antibody test alongside the thyroid function test and it will be useful in ruling out any autoimmune conditions of the thyroid.
What treatment is there if your thyroid is impacting your fertility?
If you do have a thyroid condition that is affecting your fertility, the way to combat this is to treat the thyroid disorder. For an underactive thyroid, the usual treatment is to supplement the low levels of thyroxine with levothyroxine. Alongside this, you will be asked to come in for regular blood tests until your doctor is happy with your thyroid levels.
For an overactive thyroid, treatment comes in the form of either medication, radioactive iodine treatment or surgery. However, if you are hoping to become pregnant, medication is the way to go. The main medications used are carbimazole and propylthiouracil. While these are some treatments used for thyroid disease, it may differ if you are trying to conceive, It is important to let your GP know if you have thyroid disease and plan to become pregnant as they will most likely refer you to a specialist as you will need specialist treatment and monitoring during pregnancy.
