Overactive or underactive: Your thyroid guide

The thyroid gland plays a major role in our health, but it doesn’t always function as it should. Here’s how to find out if your thyroid is overactive or underactive. 

The thyroid’s role 

The thyroid gland is part of the endocrine system.

It sits at the base of the throat and produces hormones, the two primary ones being thyroxine (T4) and tri-iodothyronine (T3) which control metabolism.

Not only do these hormones regulate the body’s weight, but they also control such vital functions as breathing, temperature control and heart rate.

What causes thyroid issues?

Too much or too little of these hormones in your body can cause thyroid issues, affecting your general health and causing symptoms such as weight loss or weight gain.

Symptoms vary depending on whether you have an overactive or underactive thyroid (see below for a list of signs to look out for).

If you do have an issue with your thyroid, you’re certainly not alone.

Thyroid issues occur in 10 per cent of the population, mostly in people over the age of 40.

Autoimmune disorders such as Hashimoto’s disease can cause thyroid problems, as can a deficiency in iodine.

Viral and bacterial inflammation can disrupt the thyroid, with benign and malignant tumours on the thyroid gland also causing issues.

There are genetic factors, and pregnancy can also be a cause – some women develop gestational thyroid disorders.

Women who have Graves’ disease have a 1 to 5 per cent risk of developing fetal hyperthyroidism (an overactive thyroid).

More women experience thyroid issues than men do. Endocrinologist Dr Stephen Thornley estimates it to be around the 10 to one mark.

While it’s unclear why women are more susceptible than men, naturopath and nutritionist Jess Blair says it’s believed there is a connection between female hormones and thyroid health.

Estrogen dominance (which can occur after progesterone levels decline, which generally starts happening around the age of 35) is thought to be linked to thyroid problems.

But how do you know if your thyroid is working as it should? 

Signs and symptoms of thyroid problems

Perhaps you’ve noticed a change in your body, tiredness, constipation or perhaps diarrhoea, increased sensitivity to the cold or heat.

If so, a visit to your doctor and a blood test is recommended to check the functioning of your thyroid.

As most thyroid disease is genetic, if you have a family history of thyroid disease, it’s worth being proactive.

“Diagnosis often comes down to a good GP thinking about thyroid disease or the patient doing some research,” says Dr Thornley.

Overactive thyroid (hyperthyroidism) 

As the name suggests, an overactive thyroid produces more hormones than are needed.

Signs to look out for:

  • Nervousness
  • Rapid weight loss
  • Irregular or fast beating heart
  • Tremors
  • Heat intolerance
  • Thinning hair
  • Diarrhoea

Underactive thyroid (hypothyroidism)

On the flipside, an underactive thyroid doesn’t produce enough hormones.

Signs to look out for:

  • Unexplained weight gain
  • Intolerance to the cold
  • Difficulty concentrating
  • Fatigue
  • Depression
  • Slower heart rate
  • Change of bowel movements (often slower digestion) 

How thyroid problems are treated

Dr Thornley says an overactive thyroid can be treated with medicine or surgery, depending on the cause.

For an underactive thyroid, a thyroxine supplement is sometimes prescribed.

Jess says a naturopath can help balance hormones, while a nutritionist can advise on the best foods to eat to support thyroid health.

“Sufficient iodine is needed for a well-functioning thyroid,” she says.

“Diet, lifestyle, supplements and herbs can really help with the health of the patient and eliminate symptoms.”

“Medication however is sometimes necessary in conjunction with natural therapies and work well together.”

Written by Samantha Allemann.