Hashimoto’s Thyroiditis: What Patients Should Know

What is Hashimoto’s thyroiditis?

In Hashimoto’s, the immune system attacks the thyroid. Inflammation can gradually reduce the gland’s ability to make hormone. The condition is also called autoimmune or chronic lymphocytic thyroiditis.

Hashimoto’s describes the underlying disease. Hypothyroidism describes low thyroid function, which can have several causes. The two terms are related, but do not mean the same thing.

Symptoms and changes over time

Some people have no symptoms at first. An enlarged thyroid, called a goiter, may cause fullness in the neck. If thyroid hormone levels fall, symptoms can include fatigue, constipation, feeling cold, dry skin, or weight gain. These symptoms can also have other causes.

What do the tests mean?

TSH and free T4 help show how well the thyroid is working. Thyroid antibodies, especially thyroid peroxidase antibodies (TPO antibodies), can help identify an autoimmune cause. An ultrasound is sometimes useful, but is not required for everyone.

Positive antibodies with normal thyroid function do not by themselves mean you need thyroid hormone. Repeated antibody measurements are usually unnecessary; monitoring thyroid function is more useful. Read about thyroid blood tests.

Monitoring and treatment

When thyroid function is normal, a clinician may recommend follow-up blood tests. Mild abnormalities require an individual decision. If Hashimoto’s causes hypothyroidism, levothyroxine replaces the missing hormone.

Take medicine consistently as prescribed. Food, calcium, iron, and other medicines can affect absorption. Discuss timing with your clinician and do not change the dose yourself. Tell your care team if you are pregnant or planning pregnancy.

Why do my Hashimoto’s symptoms sometimes get worse?

People sometimes use “Hashimoto’s flare-up” to describe a period of worse fatigue, brain fog, aches or other symptoms. The label does not by itself explain the cause or show that thyroid autoimmunity has suddenly increased.

New or worsening symptoms deserve attention, even if previous thyroid tests were normal. Your clinician may consider:

• Thyroid function: TSH and free T4 can help show whether thyroid hormone levels have changed. Symptoms alone cannot establish that your thyroid is underactive or that your medicine dose needs to change.
• How medicine is taken: missed doses, changes in timing, and interactions with food, supplements or other medicines can affect treatment. Review how you take levothyroxine with your clinician or pharmacist.
• Other possible causes: sleep problems, anemia, another illness or an overlapping condition can also cause symptoms. Further testing depends on your symptoms and medical history.

Before a follow-up visit, note when the symptoms started, how they affect daily life, and any recent illness or changes to medicines or supplements. Ask whether thyroid tests should be repeated and what else should be assessed. Do not change your thyroid medicine dose on your own.

Normal thyroid test results do not make your symptoms unimportant. The next step is to work with your care team to understand the cause and make a plan.

Research on inflammation and symptoms

Dr. Guttler highlights recent research into whether treatments that affect inflammation and the immune response can lower thyroid antibodies and improve symptoms. Some studies report both, but the findings are not consistent enough to establish a routine treatment for everyone with Hashimoto’s.

A 2024 study found that higher thyroid antibody levels were associated with inflammation, more symptoms, and poorer quality of life even when thyroid function was normal. It did not test a treatment or prove that inflammation caused every symptom. Read the study on antibodies and symptoms.

A small 2022 randomized trial tested an herbal preparation alongside levothyroxine. It reported lower antibody levels and improvements in some mood and quality-of-life measures. Fifty people entered the study, and follow-up was limited. Larger studies are needed to establish lasting benefit and safety. Read the treatment trial.

Lower antibodies do not necessarily mean better symptoms. In a larger 2024 trial of 412 people, selenium lowered TPO antibodies but did not improve quality of life more than placebo. These findings support continued research, rather than self-treatment with supplements or herbs. Discuss persistent symptoms and any proposed treatment with your clinician. Read the selenium trial.

Diet and supplements

Too much iodine, including from kelp or iodine supplements, can worsen autoimmune thyroid problems. Pregnancy has different iodine needs, so discuss supplements with your clinician.

Vitamin D, selenium, and dietary changes are being studied. Research findings do not establish a supplement or restrictive diet as a routine treatment for everyone with Hashimoto’s. Share any supplements you take with your care team.

Questions to ask your clinician

• Is my thyroid function normal, mildly abnormal, or low?
• Which tests should be repeated, and when?
• Do I need medicine now, or monitoring?
• What else should we evaluate if symptoms persist?
• Could my supplements affect my thyroid or treatment?
• How would pregnancy plans change my follow-up?