Hypothyroidism and hyperthyroidism

Hypothyroidism is a consequence of thyroid gland decreased activity, which means that it does not produce enough thyroid hormones and therefore slows overall metabolism rate.

Meanwhile, hyperthyroidism is the result of an overactive thyroid gland, which secretes excessive amounts of thyroid hormones and causes metabolism rates to speed up.

Thyroid disorders are usually controlled with medications and have a very favorable prognosis. In addition to their effect in thyroid hormones level normalization, these treatments remedy hypothyroidism and hyperthyroidism symptoms and restore fertility in a short time.

Thus, thyroid gland function monitoring is crucial to achieve and maintain a healthy pregnancy.

What is hypothyroidism and hyperthyroidism?

The thyroid is a butterfly-shaped gland located at the front of the neck, below the Adam’s apple. It produces, stores and releases two hormones (: T4 or thyroxine and triiodothyronine or T3) that regulate our body’s metabolism.

Thyroid disorders can affect any organ system in the body and are eight times more common in women. They are classified into two main groups: hypothyroidism and hyperthyroidism.

Hypothyroidism is a consequence of a thyroid gland decreased activity. This means it does not produce enough thyroid hormones and therefore slows overall metabolism rate.

Meanwhile, hyperthyroidism is the result of an overactive thyroid gland, which secretes excessive amounts of thyroid hormones and causes excessive metabolism acceleration.

Main symptoms of hypothyroidism and hyperthyroidism

By metabolism alteration, both hypothyroidism and hyperthyroidism cause disorders in ovulation, menstrual cycles and embryo implantation, consequently affecting a women’s fertility.

Other hypothyroidism symptoms are:

  • Weakness or fatigue
  • Accelerated weight increase
  • Decreased libido
  • Cold sensitivity
  • Muscle or joint pain
  • Hair loss and brittle nails
  • Pale or dry skin
  • Face, hands and/or feet swelling
  • Constipation
  • Decreased heart rate
  • Hyperprolactinemia (elevated prolactin hormone level in blood)
  • Depression
  • Slower movement and speech
  • Concentration and memory decrease

On the contrary, some of the main symptoms of hyperthyroidism are:

  • Accelerated Weight Loss
  • Increased heart rate and blood pressure
  • Heat sensitivity or intolerance
  • Excessive sweating
  • Frequent bowel movements
  • Osteoporosis
  • Brittle hair
  • Muscular weakness
  • Nervousness and anxiety
  • Irritability
  • Insomnia
  • Shivering
  • Menstrual disorders
  • Decreased fertility in women

Under treatment, thyroid disorders do not affect a normal pregnancy development. When not controlled, however, these can cause complications such as abortions, preeclampsia, placental abruption, premature birth, repeated pregnancy loss or low birth weight.

Hypothyroidism and hyperthyroidism causes

The most common cause of hypothyroidism is thyroiditis (or thyroid swelling), which affects this gland cells and hinders its normal function. Although thyroiditis can be caused by viral infections, a condition known as Hashimoto’s thyroiditis (in which the immune system attacks the thyroid gland) is the most common reason.

Other common causes of hypothyroidism are:

  • Birth defects
  • Radiation therapy
  • Surgical removal of a part or all of the thyroid gland
  • Drugs such as amiodarone and lithium (causing hypothyroidism mostly in patients who already have a genetic predisposition)
  • Insufficient dietary iodine intake
  • Damage to the pituitary gland, which regulates thyroid function

On the other hand, 70% of cases of hyperthyroidism are caused by Graves’ disease, which usually affects women between 30 and 40 years old and is caused by antibodies which stimulate thyroid growth and cause it to secrete too much thyroid hormones.

Other conditions that can cause hyperthyroidism are:

  • Excessive dietary iodine intake
  • Thyroid nodules or cysts (adenomas)
  • Thyroiditis (or thyroid inflammation)
  • Pituitary benign tumors

These conditions can be easily treated. However, if the dose is incorrect, medications for hyperthyroidism can cause hypothyroidism and medications for hyperthyroidism can cause hypothyroidism.

It is important to note that thyroid disease can also be hereditary. Thus, patients with relatives who suffer these conditions are more likely to develop them.

How hypothyroidism and hyperthyroidism diagnosed?

Thyroid disorders diagnosis is very simple: Your doctor will begin by examining your neck to determine if your thyroid is smaller or larger than normal. It will also assess your skin, your eyes, your weight, your heart rate and your temperature for other hypothyroidism or hyperthyroidism symptoms.

A blood test to measure thyroid stimulating hormone (TSH) is the most efficient test to diagnose both hypothyroidism and hyperthyroidism. This hormone is produced by the pituitary gland to regulate thyroid function. A high TSH value indicates hypothyroidism or insufficient production of thyroid hormones, while a low level of TSH reveals hyperthyroidism or excessive production of thyroid hormones. The normal range of blood TSH concentration is between 0.5 and 3.5 µIU/ml.

In some cases, the diagnosis may require a thyroid ultrasound to rule out the presence of nodules or other irregularities.

Treatments to achieve pregnancy when you suffer from hypothyroidism or hyperthyroidism

In most cases thyroid disorder treatment is safe and simple.

Hypothyroidism is usually controlled with synthetic thyroid hormones such as levothyroxine, which is orally administered in order to replenish the lack of hormones. Your doctor will ask you to take a low dose and to gradually increase it until your thyroid hormones level goes back to normal.

In addition to a regular thyroid hormone level monitoring, most people with hypothyroidism have to take synthetic thyroid hormones throughout their life.

The treatment of hyperthyroidism, however, is done with antithyroid drugs that effectively reduce the amount of thyroid hormones that the body is producing, relieving these disorder symptoms without causing permanent damage to the thyroid gland. Sometimes the use of beta blockers is also needed to regulate the patient’s heart rate until its hyperthyroidism can be controlled.

Certain cases of hyperthyroidism also require the use of radioactive iodine to destroy parts of the thyroid gland to stop the excessive hormone production. It also may require surgery to remove part or the entire thyroid, in which case the patients will have to take synthetic thyroid hormone throughout their life.

Treatment of thyroid disorders has a very favorable prognosis, normalizing thyroid hormone levels and remediating symptoms to restore fertility in a short time.

However, if these treatments are not enough, in vitro fertilization (IVF) makes it possible to obtain a patient’s eggs directly from the ovaries to fertilize them, create embryos and to transfer them back into the patient’s uterus to facilitate pregnancy.

Once you achieve pregnancy you must be carefully monitored by a specialist in maternal fetal medicine, who will monitor the behavior of your thyroid during your pregnancy through a blood thyroid profile every 6 weeks. This will help you keep your levels of thyroid hormones under control and thus avoid any thyroid related complications.