Hashimoto's Thyroiditis

Hi, I’m Dr. Melissa Lechner, an endocrinologist at UCLA Health. Today I want to talk with you about one of the most common thyroid conditions we see—Hashimoto’s thyroiditis.

If you've recently been told you have Hashimoto’s, or if you’re just trying to learn more about it, you're not alone. This is actually the most common cause of an underactive thyroid, especially in the U.S., and it affects millions of people, most often women.

So, what exactly is Hashimoto’s thyroiditis?

Hashimoto’s is an autoimmune condition. That means your immune system—your body’s defense system—mistakenly starts attacking your thyroid gland. Over time, this chronic inflammation can cause your thyroid to become underactive, a condition we call hypothyroidism.

It tends to develop slowly, and many people don’t notice symptoms at first. But as thyroid hormone levels drop, you may start to feel more tired, gain weight, feel cold all the time, or notice dry skin, constipation, or even mood changes like depression or brain fog. Some people also notice hair thinning or menstrual irregularities.

We usually diagnose Hashimoto’s with a blood test. We check your levels of TSH, which is the signal from your brain that tells the thyroid to make hormone. If your TSH is high and your thyroid hormone levels—specifically free T4—are low, that tells us your thyroid isn’t doing its job. We also check for thyroid antibodies, like TPO antibodies, which confirm the autoimmune cause.

One of the most common questions I get is: Do I need to treat this?

The answer depends on where your thyroid function is. If your thyroid hormone levels are still in the normal range and you’re not having symptoms, we may just watch it over time. But if you’re already showing signs of hypothyroidism or your levels are abnormal, we usually recommend starting thyroid hormone replacement—typically a daily pill called levothyroxine.

This is the same hormone your body normally makes, just given in a synthetic form. It’s safe, it’s effective, and for most people, once we find the right dose, it completely restores normal thyroid function.

It’s important to know that Hashimoto’s is a lifelong condition, but it’s very manageable. Many people do just fine with regular follow-up and consistent medication.

Some patients ask if there’s a diet or supplement that can help. In general, there’s no special diet that cures Hashimoto’s, but we do recommend a healthy, balanced diet and making sure you're getting enough iodine and selenium, which support thyroid health. However, most people in the U.S. already get enough iodine from their diet, and high doses of supplements are not recommended without medical guidance.

Occasionally, people with Hashimoto’s can also have a goiter, or an enlarged thyroid. That may cause a feeling of fullness in the neck or a visible swelling, but it’s usually not dangerous. We can monitor the size with a neck ultrasound if needed, but in most cases, it doesn’t require surgery or other intervention.

One other thing I’ll mention—Hashimoto’s can sometimes run in families, and it’s associated with other autoimmune conditions like type 1 diabetes or celiac disease, so if you or a family member has those, your risk may be slightly higher.

To recap:

Hashimoto’s is the most common cause of hypothyroidism, and it’s due to autoimmune inflammation of the thyroid
It can cause symptoms like fatigue, weight gain, constipation, and feeling cold
We diagnose it with blood tests, including TSH, free T4, and thyroid antibodies
Treatment is usually with a daily thyroid hormone pill, which is safe and effective
It’s a lifelong condition, but very manageable with regular follow-up
And while there’s no special cure, a healthy lifestyle and proper medication make a big difference

If you’ve been diagnosed with Hashimoto’s and have questions about your thyroid levels, your symptoms, or your treatment plan, we’re here to help.

To schedule an appointment with our team, visit us at endocrinology.uclahealth.org, or call us at 310-825-2631.

Thanks for watching—I’m Dr. Melissa Lechner. Take care and be well.