Body & Fitness

How your thyroid can affect your energy levels and general health

An important part of your hormonal system, the thyroid gland can be responsible for a range of symptoms, from fatigue and dry skin to brain fog.

This is one of the most frequent patient stories doctors hear:

“Doctor, I feel so tired all the time. I’m not eating any differently to normal, but I seem to be putting on weight. And my hair is falling out.”

It alerts us to the possibility of a thyroid disorder – they’re reasonably common, affect women more than men and become more prevalent with age.

The butterfly-shaped thyroid gland lies at the front of your neck, below the voice box. The thyroid is part of the endocrine system, which consists of a group of glands responsible for producing hormones that help the body function properly.

It does this by producing two iodine-containing hormones – thyroxine (T4) and triiodothyronine (T3) – which control the body’s processes, such as heart rate, digestion, body temperature and weight.

The thyroid uses iodine from foods to produce these hormones, and iodine deficiency is the most frequent cause of thyroid disorders.

In New Zealand, iodine deficiency is relatively common because iodine levels are very low in our soils where we grow vegetables and grains and raise livestock. However, you can boost your iodine levels by eating dietary sources including dairy, eggs, seafood, seaweed, some vegetables and bread fortified with iodised salt.

What can go wrong with your thyroid?


When the thyroid is underactive as it doesn’t produce enough hormone.

What you notice: Symptoms may be subtle or obvious. They include fatigue, weight gain, constipation, dry skin and hair, hoarseness, high cholesterol level, stiff joints, muscle weakness, depression, brain fog, intolerance to cold weather, infertility in women and period changes. There may be a goitre – a diffuse generalised swelling.

What to do: See your doctor to investigate via a blood or urine test or ultrasound. Treatment is thyroid hormone replacement tablets, regularly monitored to ensure the right hormone levels.


Nodules are lumps that grow in the thyroid tissue and you may see a lump that moves with swallowing. Most are benign but if a nodule looks suspicious on ultrasound, a needle biopsy will be necessary.

Nodules will be monitored regularly with ultrasound and abnormal thyroid function needs medication.

If a nodule is suspicious you will be referred for specialist advice.

Hyperthyroidism (Thyrotoxicosis)

When the thyroid produces too much hormone, which speeds up your metabolism. The most common cause is Graves’ disease, an autoimmune condition.

What you notice: Anxiety, agitation, weight loss, palpitations, diarrhoea, absent or irregular periods and intolerance of hot weather.

What to do:Your doctor will arrange thyroid function testing. Usual treatment is a medication called neomercazole. Radioactive iodine or surgery may be needed.


A goitre is an enlargement of the thyroid gland.

What you notice: There may be a swelling in the front of your neck. Depending on its size, a goitre may cause you to have a cough, hoarseness or difficulty swallowing. You may have symptoms of overactive or underactive thyroid.

Causes:Iodine deficiency, autoimmune thyroid disease, cyst or nodules, or thyroid cancer.

What to do:Your GP will arrange a blood test for thyroid function, thyroid antibodies and an ultrasound. If there is a suspicious nodule it will be biopsied.


Thyroiditis refers to inflammation of the thyroid gland. This is an autoimmune process where the body’s immune system attacks the thyroid gland and is usually referred to as Hashimoto’s thyroiditis or Hashimoto’s disease. It may run in families. Typically it involves a period of overactivity of the thyroid followed by hypothyroidism. Treatment is needed to control symptoms.

Thyroid cancer

There are five types of thyroid cancer: papillary, follicular, medullary, anaplastic and thyroid lymphoma.

What you notice: A goitre, signs of hyperthyroidism, changes in your voice, cough or trouble swallowing.

What to do: Your doctor will arrange an ultrasound and needle biopsy. Treatment options include surgery to remove the thyroid gland, and radioactive iodine. After the thyroid is removed, lifelong thyroid hormone replacement therapy is needed.

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