Hair Loss and Thinning Hair: Is Your Thyroid to Blame?

Watching your hair fall out in clumps or noticing your once-thick hair becoming thin and brittle can be deeply unsettling. While hair loss has many causes, your thyroid — a small butterfly-shaped gland in your neck — might be the hidden culprit behind your changing hair.

Why This Symptom Matters

Your thyroid produces hormones that control your metabolism, affecting nearly every cell in your body — including your hair follicles. When thyroid hormone levels are too low (hypothyroidism) or too high (hyperthyroidism), your hair growth cycle gets disrupted.

In hypothyroidism, hair often becomes dry, brittle, and falls out more than usual. You might notice thinning all over your scalp, not just in specific spots. The outer third of your eyebrows may also thin or disappear entirely — a classic sign that many people overlook.

With hyperthyroidism, hair typically becomes fine and soft, breaking easily. Hair loss tends to be more diffuse, affecting the entire scalp rather than creating bald patches like other types of hair loss.

The good news? Thyroid-related hair loss is usually reversible once hormone levels return to normal. However, it can take several months for your hair growth cycle to reset, so patience is key.

Could It Be Your Thyroid?

Hair loss isn’t always thyroid-related. Genetics, stress, hormonal changes (like pregnancy or menopause), certain medications, and nutritional deficiencies can all cause hair to fall out or thin. Autoimmune conditions like alopecia areata create distinct bald patches, while androgenic alopecia typically follows predictable patterns.

However, thyroid testing makes sense if your hair loss comes with other symptoms like unexplained fatigue, weight changes, mood shifts, or feeling unusually hot or cold. Women are five to eight times more likely to develop thyroid problems than men, especially after age 35.

You’re at higher risk for thyroid issues if you have a family history of thyroid disease, other autoimmune conditions, or have been pregnant within the past year. If your hair loss seems sudden or severe, or if you’re noticing other unexplained health changes, a thyroid test can provide valuable insights.

What Tests Should You Consider?

For hair loss concerns, a comprehensive thyroid panel gives you the clearest picture. TSH (thyroid stimulating hormone) is the standard screening test, but it doesn’t tell the whole story. Free T4 and Free T3 measure the actual thyroid hormones available to your cells.

Thyroid antibody tests (TPO and thyroglobulin antibodies) can detect autoimmune thyroid conditions like Hashimoto’s disease, which is a common cause of hypothyroidism and related hair loss.

What to Expect from Testing

Modern thyroid testing is surprisingly simple. You can order comprehensive panels online without a doctor’s visit, then visit a nearby lab for a quick blood draw. Most testing services provide results within 1-3 business days through a secure online portal.

Your results will show whether your thyroid hormone levels fall within normal ranges, along with clear explanations of what the numbers mean. Many services also provide guidance on next steps if results suggest thyroid dysfunction.

When to See a Doctor

Seek medical attention promptly if you experience sudden, severe hair loss, especially if it’s accompanied by other concerning symptoms like rapid weight loss, heart palpitations, or extreme fatigue. If you’re losing hair in distinct patches rather than general thinning, this could indicate an autoimmune condition that needs different treatment.

Even if your thyroid tests come back normal, persistent hair loss warrants professional evaluation to explore other potential causes and treatment options.

This content is for informational purposes only and does not constitute medical advice. Always consult a healthcare provider for diagnosis and treatment.