Managing hyperthyroidism

By Dr Erick Njenga, Consultant Physician and Endocrinologist at Aga Khan University Hospital, Nairobi

Do you experience unexplained weight loss, a rapid heartbeat, unusual sweating, heat intolerance, insomnia, anxiety symptoms, mood lability, thinning of hair, skin changes especially darkening and hardening at the shins and ankles, disappearing or scanty periods for women, or other unexplained signs and symptoms? Then you could be suffering from hyperthyroidism.

What is hyperthyroidism?

This is a condition normally characterised by overproduction of thyroid hormones by the thyroid gland that is located at the front of the neck.

What are the common symptoms to look out for?

Thyroid hormone plays a crucial role in regulating various body functions. When the thyroid hormone is in excess, it tends to affect different systems in the body.

In the central nervous system, it can cause tremors, muscle weakness, mood lability as well as anxiety. It can cause symptoms within the eye, where it causes a condition called grave’s disease. This happens when abnormal antibodies are produced and cause what’s called graves ophthalmopathy, which tends to affect the muscles of the eye and lead to excess fat deposition at the back of the eyeball. As a result, the eyes pop outward. This is called proptosis. Sometimes they can cause the eyelids to lag behind and also to be retracted. These characteristic signs of hyperthyroidism in the eye can further affect one’s ability to see in the long run.

In the heart, hyperthyroidism can cause a very rapid heart rate and can lead to heart failure in the long run. It can also cause an abnormal heart rhythm.

In the gastrointestinal tract, we normally tend to have increased motility of the gastrointestinal system. This can lead to an increased frequency of loose stool.

Looking at the genitourinary tract in women, for instance, it can affect their fertility by disrupting their menstrual cycles. Hyperthyroidism can make periods/menstruation scant or to disappear for long. It can also lead to first-trimester pregnancy losses.

Other body parts like the skin will tend to get some characteristic skin changes, which include darkening and hardening of the skin. This is seen in the anterior aspect of the shins and ankles, and is called pretibial myxedema. Those with heart failure can also have swelling of the ankles associated with excess thyroid hormone.

Hyperthyroidism also has psychiatric manifestations. For instance, you can get manic episodes, restlessness, and insomnia. These are the common manifestations we see in patients.

In the fingers, one can get some swellings, sweating in the palms, and tremors.

There’s also significant unexplained weight loss, which is normally due to an increase in the basal metabolic rate in the setting of hyperthyroidism.

What are some subtle symptoms that are easy to miss?

In the early stages of hyperthyroidism, it is possible that you can miss out on some of the symptoms. The eye signs can be missed. Sometimes the rapid heart rate may not be picked up early, and other times, people may not exhibit any swelling of the thyroid gland, commonly known as a goiter.

It is also possible to have manifestations of hyperthyroidism without a goitre.

What causes hyperthyroidism in pregnancy

Once people have underlying Graves’ disease, which is an autoimmune cause of hyperthyroidism, it can worsen in the setting of pregnancy. This can be seen in the first trimester of pregnancy, or after delivery, or even within the first six weeks upon giving birth. There can be flares of the disease where the hormones are significantly elevated.

How can expectant women with hyperthyroidism be managed?

We have to take extreme caution for mothers with underlying hyperthyroidism in the setting of pregnancy. We tend to adjust the doses of the thyroid medication. This balancing of medication dosage ensures that we don’t cause hypothyroidism to the foetus. The dosage is slightly reduced to keep the mother slightly hyperthyroid but monitor her thyroid function test throughout the entire pregnancy.

We also keep track of the antibody levels because if they are very high, they can sometimes be transmitted to the foetus and lead to hyperthyroidism in the foetus.

When the mother delivers, we check the mother’s thyroid test to ensure that all is well, to avoid hyperthyroidism, or what is referred to as foetal or neonatal hyperthyroidism if the antibodies were high during the pregnancy.

The choice of medication is also key, where we tend to switch from carbimazole or methimazole to Propylthiouracil in the first 12 weeks of pregnancy to avoid foetal malformations. We then switch back to carbimazole after 12 weeks when the baby is fully formed, and maintain this through the pregnancy with appropriate dose adjustments every four weeks.

Mothers with pre-existing hyperthyroidism must also carefully plan with their endocrinologist and gynaecologist for future pregnancies. They must undergo preconception counselling and ensure that their thyroid hormones are as near normal as possible to avoid first-trimester miscarriages.

The other common complication that we tend to worry about regarding hyperthyroidism is what’s referred to as a thyroid storm. This can be triggered by stressful events like surgery, pregnancy, etc. When it’s not well controlled, it can lead to very high levels of hyperthyroid hormones. This can result in cardiovascular complications, including abnormal heart rhythm. It can also precipitate heart failure. Very high levels of hyperthyroid hormones may also cause hyperthermia, which is a critical condition that should be managed in the critical care unit to support the patient in terms of blood pressure by giving fluids aggressively to reduce the thyroid hormones in the system.

Definitive treatment involves the use of anti-thyroid medications such as carbimazole or methimazole, as well as Propylthiouracil, which is a second-line drug usually reserved for the first trimester of pregnancy and for those who develop complications or allergic reactions to carbimazole.

Radio iodine treatment is considered the gold standard of treatment and can be offered in Kenya. We ensure that one has normal thyroid tests before the procedure is offered, and that one does not have active eye disease. One should avoid pregnancy for at least six months after the procedure. Monitoring for hypothyroidism thereafter should be done. This occurs at the rate of four percent per annum. When this happens, we replace the thyroid hormone (Levothyroxine).

What are the risk factors for hyperthyroidism?

• Family history is a strong risk factor.
• Genetic predisposition.
• History of having positive thyroid antibodies.
• Having other autoimmune conditions such as lupus, type 1 diabetes or rheumatoid arthritis.
• Women are more predisposed to developing hypothyroidism compared to men. It’s approximately 3-4 times more common in women than men, usually due to high oestrogen levels.
• There are other medications used that may contain iodine, such as amiodarone, which is used to manage abnormal heart rhythms, and can predispose one to hyperthyroidism.

How can I protect myself from suffering from this condition?

It may not be possible to directly protect yourself from hyperthyroidism, but the key thing is to know if you have any significant risk factors mentioned above. It is advisable to monitor your thyroid function test frequently to ensure you don’t lapse into hyperthyroidism.