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Hashimoto’s thyroiditis: what it is, symptoms and how it is treated

Hashimoto’s thyroiditis is the most common cause of hypothyroidism in countries with an adequate iodine intake, such as Spain. It is an autoimmune condition in which the body’s own immune system progressively attacks the thyroid gland, ultimately reducing the production of thyroid hormones. Although many people live with it for years without realising, its effects on metabolism, weight, mood and energy can be considerable.

 

What is Hashimoto’s thyroiditis?

The thyroid is a small, butterfly-shaped gland located at the front of the neck. It produces the thyroid hormones (T4 and T3), which regulate the pace at which the body works: body temperature, heart rate, digestion and the way the body uses energy. In Hashimoto’s thyroiditis, also known as chronic lymphocytic thyroiditis, the immune system generates antibodies that damage the thyroid tissue. Over time, the gland becomes inflamed and loses the ability to produce enough hormone, resulting in hypothyroidism (an underactive thyroid).

It is a slow, silent process. In the early stages, the partial destruction of the gland can release stored hormone and cause a temporary phase of hyperthyroidism (sometimes called “hashitoxicosis”), which then progresses towards sustained hypothyroidism. This condition affects women far more often than men and is usually diagnosed between the ages of 30 and 60, although it can appear at any age.

 

Causes and risk factors

There is no single known cause. Hashimoto’s thyroiditis arises from a combination of genetic predisposition and environmental factors that trigger the autoimmune response. The factors that increase the risk include:

  • Being a woman: the risk is several times higher than in men.
  • A family history of thyroid disease or of other autoimmune conditions.
  • Already having another autoimmune condition, such as type 1 diabetes, coeliac disease, rheumatoid arthritis or vitiligo.
  • Hormonal changes, particularly during pregnancy and the postnatal period.
  • Excess iodine in the diet and certain environmental factors.

It is worth bearing in mind that autoimmune conditions tend to be associated with one another, so a diagnosis of Hashimoto’s justifies keeping an eye out for other related disorders.

 

Symptoms of Hashimoto’s thyroiditis

Because the fall in thyroid hormone is gradual, symptoms appear little by little and are often put down to stress, age or a busy lifestyle. The most common are:

  • Persistent tiredness and a lack of energy.
  • Weight gain with no clear change in diet, due to a slowing of the metabolism. This is one of the most frequent concerns: it is important to distinguish this mechanism from other metabolic disorders such as insulin resistance.
  • Sensitivity to cold, along with cold hands and feet.
  • Dry skin, brittle nails and hair loss.
  • Constipation.
  • Muscle and joint pain.
  • Low mood, difficulty concentrating or “brain fog”.
  • Irregular or heavier menstrual cycles.
  • An enlarged thyroid (goitre), felt as a sensation of pressure in the neck.

The severity varies greatly from one person to another. Some patients barely notice any discomfort, whereas in others the hypothyroidism clearly affects their quality of life.

 

How is it diagnosed?

Diagnosis is based on a combination of the clinical history and a blood test. The key tests are TSH (thyroid-stimulating hormone), which is usually raised when the gland is underactive; free T4, which may be low; and the antithyroid antibodies (anti-TPO and antithyroglobulin), whose presence confirms the autoimmune origin. The assessment is sometimes completed with a thyroid ultrasound scan to evaluate the size and structure of the gland. You can find reliable, easy-to-understand information about this condition on MedlinePlus and at the Spanish Society of Endocrinology and Nutrition (SEEN).

 

Treatment of Hashimoto’s thyroiditis

The treatment of hypothyroidism caused by Hashimoto’s is simple and effective: it consists of replacing the hormone that the thyroid no longer produces in sufficient quantity with levothyroxine, a synthetic thyroid hormone identical to the natural one. It is taken once a day, on an empty stomach, and the dose is adjusted individually with regular TSH checks until the optimal amount is found. In most cases treatment is lifelong, but it allows a completely normal life.

It is important not to change or stop the medication on your own and to keep to your reviews, as your needs may change over time, or with weight or pregnancy. As for lifestyle, maintaining a balanced diet and a healthy weight supports general wellbeing, although no supplement replaces hormone treatment when this is needed. Any supplement (for example, selenium or iodine) should always be discussed with the specialist.

 

What if I have Hashimoto’s and I’m pregnant?

Hashimoto’s thyroiditis deserves particular attention in women of childbearing age. Uncontrolled hypothyroidism can make it harder to conceive and increase the risk of complications during pregnancy, so levothyroxine requirements usually rise during pregnancy and call for closer monitoring. If you have the diagnosis and are planning a pregnancy, it is important to discuss it with your doctor so that treatment can be adjusted in advance.

Day to day, living with Hashimoto’s is perfectly compatible with an active, normal life. It helps to keep to a good sleep routine, manage stress, exercise regularly and follow a balanced diet. It is also advisable to avoid excess iodine from seaweed or unindicated supplements, as this can worsen thyroid function in people who are predisposed. If new or persistent symptoms appear — marked tiredness, changes in weight, changes in mood — it is best to seek advice and check your hormone levels rather than simply putting them down to a busy lifestyle.

 

Are there complications if it is left untreated?

Untreated hypothyroidism can have consequences beyond tiredness: it raises cholesterol and, with it, cardiovascular risk; it can make blood pressure harder to control — a link we cover in our article on hypertension and diabetes; and, in pregnant women, it increases the risk of complications for both mother and baby. That is why it is so important to detect and treat it in good time. Poorly controlled hypothyroidism can also contribute to some of the chronic conditions associated with metabolic disorders.