Millions of people worldwide live with hypothyroidism and Hashimoto's thyroiditis, conditions that often go undiagnosed despite their significant impact on daily life.
According to Dr Konstantinos Segkos, consultant endocrinologist and director at Metropolitan General, hypothyroidism affects an estimated 5 to 12 per cent of the population, while Hashimoto's thyroiditis is even more common.
What are Hashimoto's and hypothyroidism?
The thyroid gland, located at the front of the neck, produces hormones that regulate the body's metabolism and influence the functioning of virtually every organ.
When the thyroid becomes underactive, the condition is known as hypothyroidism.
Hashimoto's thyroiditis is an autoimmune disease in which the immune system mistakenly attacks the thyroid gland. Over time, this damage can impair the gland's ability to produce hormones, leading to hypothyroidism.
Hashimoto's is the most common autoimmune disease and has a strong hereditary component.
Not everyone with Hashimoto's develops hypothyroidism immediately. It may take months, years or even decades for thyroid function to decline. However, among people who have not had their thyroid removed, Hashimoto's accounts for more than 95 per cent of hypothyroidism cases.
Symptoms of hypothyroidism
Because thyroid hormones affect the entire body, hypothyroidism can produce a wide range of symptoms, including:
- Persistent fatigue
- Low energy levels
- Brain fog and difficulty concentrating
- Drowsiness
- Weight gain or difficulty losing weight
- Sensitivity to cold
- Dry skin
- Hair thinning and hair loss
- Constipation
- Slower heart rate
- Swelling
In women, the condition may also cause:
- Menstrual irregularities
- Infertility
- Pregnancy complications
Untreated hypothyroidism can also affect blood pressure, cholesterol levels and cardiovascular health. In severe cases, it can lead to a life-threatening condition known as myxoedema coma.
Hashimoto's itself generally causes symptoms only when it results in hypothyroidism, although menstrual and fertility problems may occur even before thyroid function is affected.
How is it diagnosed?
Hashimoto's thyroiditis is diagnosed through:
- Blood tests for anti-TPO and anti-TG antibodies
- Thyroid ultrasound, which can reveal characteristic changes in the gland
Hypothyroidism is diagnosed through thyroid function tests, including:
- TSH
- Free T4
- In some cases, Free T3 or Total T3
These tests are also used to monitor treatment effectiveness.
Treatment
The primary treatment for hypothyroidism is levothyroxine, a synthetic version of the thyroid hormone T4.
For approximately 90 to 95 per cent of patients, treatment leads to a complete resolution of symptoms.
A smaller group, around 5 to 10 per cent, may continue experiencing symptoms despite treatment. In these cases, doctors may consider combining levothyroxine (LT4) with liothyronine (LT3) under careful medical supervision.
Liothyronine is not recommended during pregnancy, as it does not cross the fetal blood-brain barrier. Patients with cardiovascular disease must also be monitored closely when using it.
Thyroid hormone levels are typically rechecked six weeks after starting treatment or adjusting dosage. Once the correct dosage has been established, follow-up testing is usually carried out every six to twelve months.
There is currently no cure for Hashimoto's thyroiditis itself.
Why might symptoms persist despite treatment?
According to Dr Segkos, patients may continue feeling unwell for several reasons:
- Incorrect dosage of thyroid hormone, even when blood tests appear normal in some special cases.
- Incorrect diagnosis, with studies suggesting that up to one in three people receiving thyroid hormone treatment may not have true hypothyroidism.
- The presence of another undiagnosed condition with symptoms similar to those of hypothyroidism.
Special considerations in pregnancy
The management of Hashimoto's and hypothyroidism differs in women who are pregnant or struggling with infertility, as both conditions can independently affect fertility and pregnancy outcomes.
Pregnant women with hypothyroidism often require an immediate increase in thyroid hormone dosage once pregnancy is confirmed because hormone requirements rise significantly.
They also require frequent laboratory monitoring to reduce the risk of complications such as:
- Preeclampsia
- Premature birth
- Miscarriage
- Low birth weight
- Impaired fetal neurological development
For this reason, close supervision by an endocrinologist is considered essential throughout pregnancy.
