Thyroid Basics: Symptoms, Tests and Treatment

Your thyroid is a small, butterfly-shaped gland at the front of your neck. It makes hormones that control your metabolism, which affects your energy, weight, heart rate, body temperature and mood. Thyroid conditions are common and are diagnosed much more often in women than in men, particularly after pregnancy and around menopause.

How the thyroid works

The thyroid makes two main hormones, thyroxine (T4) and triiodothyronine (T3). The pituitary gland in the brain controls this by releasing thyroid-stimulating hormone (TSH).

• When thyroid hormone levels are low, the pituitary releases more TSH to push the thyroid to work harder
• When thyroid hormone levels are high, TSH falls

This is why TSH is usually the first test doctors order.

Underactive thyroid (hypothyroidism)

Hypothyroidism means the thyroid is not making enough hormone. In Canada, the most common cause is Hashimoto's thyroiditis, an autoimmune condition in which the immune system attacks the thyroid.

Common symptoms develop slowly and can be mistaken for stress or ageing:

• Tiredness and low energy
• Feeling cold more than others
• Weight gain
• Dry skin and hair, or hair thinning
• Constipation
• Low mood or trouble concentrating
• Heavier or irregular periods
• Muscle aches and a slow heart rate

Overactive thyroid (hyperthyroidism)

Hyperthyroidism means the thyroid is making too much hormone. The most common cause is Graves' disease, another autoimmune condition. Thyroid nodules and inflammation of the thyroid can also cause it.

Symptoms may include:

• Fast or irregular heartbeat
• Feeling anxious, irritable or shaky
• Weight loss despite a normal or increased appetite
• Feeling hot and sweating more
• Trouble sleeping
• More frequent bowel movements
• Lighter or less frequent periods
• Bulging or irritated eyes, in Graves' disease

Thyroid problems and pregnancy

Thyroid hormone is important for a baby's development. If you have a thyroid condition and are planning a pregnancy, talk to your health care provider beforehand, as your dose of thyroid medicine often needs to increase early in pregnancy. Some people develop thyroid inflammation in the months after giving birth, called postpartum thyroiditis, which can cause temporary overactive and then underactive symptoms.

How thyroid problems are diagnosed

Diagnosis is based on your symptoms, an examination and blood tests.

• TSH is the main screening test
• Free T4, and sometimes free T3, help confirm and describe the problem
• Thyroid antibodies can point to Hashimoto's or Graves' disease
• An ultrasound may be used if a lump or enlarged thyroid (goitre) is found

Routine thyroid screening is not recommended for everyone without symptoms, so your provider will decide when testing makes sense for you.

Treatment

Hypothyroidism is usually treated with levothyroxine, a daily tablet that replaces the missing hormone. Your provider will check your TSH after starting or changing the dose, usually after about six weeks, and then periodically once you are stable.

Hyperthyroidism may be treated with antithyroid medicines, radioactive iodine or, less often, surgery. Beta-blockers can help control a fast heartbeat and tremor in the meantime.

Tips for taking levothyroxine

How you take levothyroxine affects how well it is absorbed.

• Take it at the same time every day, on an empty stomach with a glass of water, usually 30 to 60 minutes before breakfast
• Separate it by at least four hours from calcium, iron, magnesium, antacids and some cholesterol medicines
• Coffee, soy and high-fibre foods can reduce absorption, so keep your routine consistent
• Try to stay on the same product, as switching between brands can change your levels slightly, and let your provider know if a switch happens
• Do not stop taking it without talking to your provider, even if you feel better

Iodine and supplements

In Canada, table salt is iodized, and most people get enough iodine from their diet. Taking extra iodine or kelp supplements can actually worsen some thyroid conditions. Biotin, found in many hair and nail supplements, can interfere with thyroid blood test results, so tell the lab or your provider if you take it, as you may need to stop it for a few days before testing.

When to see a health care provider

Book an appointment if you have symptoms that last more than a few weeks, notice a lump or swelling in your neck, or have a family history of thyroid disease and are planning a pregnancy. Seek urgent care for a very fast or irregular heartbeat, chest pain, or severe confusion.

Our pharmacists can answer questions about your thyroid medicine any time of day.