The key to the endocrine system


In recent times, we have gained a better understanding of how our bodies work. This is particularly the case when faced with illnesses such as heart disease, lung cancer or other potentially fatal conditions. However, the endocrine system which controls many parts of the body’s functions including appetite, reproduction and stress responses remains a mystery to many.

The hormones which are released from the endocrine system have a more subtle yet hugely important impact on us both physically and psychologically. One of the key glands in the endocrine system is the thyroid gland.

A small butterfly shaped gland in the neck, it releases thyroid hormone into the blood which influences the metabolic rate of the body – basically the rate of cell growth, division and turnover of the body.



When the thyroid gland malfunctions, it either produces too much thyroid hormone leading to hyperthyroidism or too little thyroid hormone, leading to hypothyroidism. And while diagnosis of the condition is pretty straightforward once symptoms are linked to it, the problem is that some patients and doctors don’t first consider the thyroid as a possible cause of their symptoms.

One woman in her early 50s says, “I thought I was going through the menopause. My heart was racing. I was sweating. I had mood swings and insomnia. At first, I thought the menopause is more difficult than I suspected but when I had my thyroid checked, I discovered the symptoms were due to an overactive thyroid.”

Another woman in her late 50s was recovering from breast cancer treatment when she became very emotionally distressed.

“I was highly nervous about everything and doing everything at speed. I was also losing an enormous amount of weight and was very worried that the cancer hadn’t gone even though I had been given the all-clear physically.

“I was so emotionally upset that I had started to attend a psychiatrist but I didn’t feel it was a mental problem. When I finally had my thyroid checked, it was found to be hugely overactive.

“If I hadn’t had the test, I would have been admitted to hospital and had drugs treating me for what I didn’t have. Now, I’d advise people to go to their GP to have a general medical check-up following cancer treatment.”


Psychological symptoms

Prof Donal O’Shea, consultant endocrinologist at St Vincent’s University Hospital, Dublin, says that a lot of the symptoms of thyroid disease can be associated with many different medical conditions.

“The thyroid is commonly checked by GPs now especially if a patient is predominantly tired or anxious,” he says.

“But before 1970 when there were no measurements of thyroid hormone levels, patients with thyroid disease were occasionally admitted to psychiatric hospitals because of the prominent psychological symptoms before the thyroid problem was suspected,” he adds.

Blood tests to check the levels of Thyroid Stimulating Hormone (TSH) produced by the pituitary gland and thyroid hormone itself are standard ways to check whether the thyroid gland is malfunctioning.

An ultrasound or nuclear medicine scan can sometimes help to determine the activity of the thyroid gland.

Once diagnosed, there are different treatment options. The standard treatment for hypothyroidism is thyroid hormone replacement medication (thyroxine).

“For 95 per cent of patients, this treatment is relatively straightforward. There are ongoing studies to see if adding another form of thyroid hormone is beneficial for a small percentage of patients who don’t feel fully well on thyroxine,” says O’Shea. Hyperthyroidism is treated with medications (Carbimazole) which reduce the production of thyroid hormone.

“If patients have an overactive thyroid and get too much Carbimazole or if they are very sensitive to Carbimazole, their thyroid can become underactive. There is nothing worse for a patient than going from an overactive state to an underactive state very quickly,” says O’Shea.

It takes about six weeks for the medication to work and therefore patients need to be checked every six weeks in the active treatment phase.

Some patients with hyperthyroidism are also prescribed beta-blockers to slow the heart rate and reduce nervousness while the thyroid medication is taking affect. Once the thyroid hormone levels are stabilised, annual check-ups are sufficient, according to O’Shea.



A small percentage of patients will have thyroidectomy (surgical removal of part or all of the thyroid gland) if the medication doesn’t work, if there are malignant nodules in the thyroid gland or if an enlarged thyroid is restricting breathing or swallowing.

Radioiodine therapy (radioactive iodine) is another treatment for hyperthyroidism which makes the thyroid gland partially or fully inactive. Thyroxine medication is often required following surgery or radioiodine therapy to replace the thyroid hormone no long being produced by the thyroid gland.

Undergoing treatment can take its toll on the patient. “People don’t understand it. You look fine which is why thyroid problems are sometimes called invisible illnesses. You’re not in bed or in hospital yet it’s quite difficult and for many people it’s a lifelong condition which requires monitoring and management,” says one woman who has been dealing with thyroid problems for about five years now.


Normal ranges

O’Shea says that there are well established normal levels and reference ranges and targets for thyroid problems, however patients can still have symptoms for quite some time.

“You will usually get the thyroid levels right in about eight weeks but it can take a longer time for the system to get used to being normal – especially if the patient has been overactive or underactive for a long time before being diagnosed. Patients often say they are not back to themselves until about six to eight months after the hormone levels are right.

“The physical symptoms disappear quite quickly with normalised hormone levels but it takes longer for energy and anxiety levels and sleep disturbances to disappear.”


Risks and symptoms of thyroid problems

What are the risks of thyroid problems?

Anyone over 60 is at a higher risk of having thyroid problems. Women are up to seven times more likely to suffer than men and are particularly prone to thyroid problems following pregnancy and around the menopause.

A family or personal history of thyroid problems and autoimmune disease, some medications, iodine- containing food supplements and previous radiotherapy are other risk factors.


What are the different types of thyroid problems and symptoms?

Autoimmune Hyperthyroidism (previously called Grave’s disease) is the most common form of hyperthyroidism. It results from an overproduction of thyroid hormone. Its symptoms include rapid weight loss (even with a healthy appetite), sensitivity to heat, brittle nails, itch, loose bowel movements, rapid pulse, insomnia, anxiety, difficulty swallowing, difficulty concentrating (sometimes called brain fog).

Autoimmune Thyroiditis (previously called Hashimotos disease) is the most common form of hypothyroidism. It involves destruction of thyroid tissue and permanent hypothyroidism – sometimes preceded by a brief period of overactivity. Its symptoms include weight gain, lethargy, fatigue (even after a good night’s sleep), dry skin and hair, constipation, slow pulse, high cholesterol levels and difficulty concentrating.

The thyroid gland can enlarge in either of these conditions and the term for this is goitre. Benign or malignant nodules can also appear in the thyroid gland. If they are large, they will also cause goitre. Nodules can sometimes overproduce thyroid hormone causing hyperthyroidism.

A thyroid storm is a rare life-threatening crisis which occurs in 1-2 per cent of patients with hyperthyroidism. Its diagnosis is based on symptoms (not levels of thyroid hormone) which include fever, psychosis, nausea, vomiting, diarrhoea, palpitations, confusion and disorientation. It requires immediate medical treatment in an acute hospital.

The Irish Times Logo
Commenting on The Irish Times has changed. To comment you must now be an Irish Times subscriber.
Error Image
The account details entered are not currently associated with an Irish Times subscription. Please subscribe to sign in to comment.
Comment Sign In

Forgot password?
The Irish Times Logo
Thank you
You should receive instructions for resetting your password. When you have reset your password, you can Sign In.
The Irish Times Logo
Please choose a screen name. This name will appear beside any comments you post. Your screen name should follow the standards set out in our community standards.
Screen Name Selection


Please choose a screen name. This name will appear beside any comments you post. Your screen name should follow the standards set out in our community standards.

The Irish Times Logo
Commenting on The Irish Times has changed. To comment you must now be an Irish Times subscriber.
Forgot Password
Please enter your email address so we can send you a link to reset your password.

Sign In

Your Comments
We reserve the right to remove any content at any time from this Community, including without limitation if it violates the Community Standards. We ask that you report content that you in good faith believe violates the above rules by clicking the Flag link next to the offending comment or by filling out this form. New comments are only accepted for 3 days from the date of publication.