Your thyroid gland is one of the most important parts of how your body functions day to day. It's responsible for creating and producing hormones that control everything from your metabolism to the health of your heart, bones, and GI system. If things aren't right, your thyroid can be both over- and underactive, issues an estimated 20 million Americans experience, according to the American Thyroid Association. Unfortunately, women are up to eight times more likely than men to have some kind of thyroid disease.
If your body is creating too much thyroid hormone, you have hyperthyroidism; too little and it's hypothyroidism. The most commonly observed symptoms that come from an overactive thyroid are hypersensitivity to hot temperatures, weight loss, and a racing heart; while an underactive thyroid leads to tiredness, weight gain, and a hypersensitivity to cold temperatures. However, the impact of too much or too little thyroid hormone on your body can be felt in many other areas too. If your thyroid isn't working right, even your hair can feel different, with experts warning that certain changes to your locks may be a sign that something's amiss. For the full story of how your hair can function as an early warning sign of a thyroid issue, read on.
Dry, coarse, or brittle hair could be due to thyroid disease.
Hypothyroidism can cause your hair to become dry, coarse, or brittle. In his 2011 research paper "Thyroid Hormone Action on Skin" published in the journal Dermato-Endoctrinology, Joshua D. Safer, MD, listed a series of changes to the hair that can occur as a direct result of a thyroid disorder. "In hypothyroidism, hair can be dry, coarse, brittle and slow growing," he explains. Conversely, hyperthyroidism can lead to your hair feeling extra soft and fine.
The connection between your hair and your thyroid stems from the interference of thyroid hormones T3 and T4, the experts at Healthline explain. When the levels of these hormones are out of line, it affects the development of new hair at the root of your hair follicles. Usually, these roots are fed by your blood vessels to create more cells and grow your hair. But that process doesn't go as planned with a thyroid disorder.
Thyroid disease can also cause hair loss.
The impact of out-of-whack thyroid hormones on your hair can be even more severe than just breakage and dryness. The experts at Very Well Health warn that "having autoimmune thyroid disease in particular also puts you at greater risk for alopecia areata—excessive and rapid hair loss in specific parts of the scalp." According to a 2010 study published in the journal Hippokratia, 41 percent of people with hypothyroidism experienced hair loss.
While it is normal to lose a certain amount of hair every day (as many as 100 individual hairs, according to the American Academy of Dermatology Association), when caused by a thyroid disorder, it may present as thinning across the whole scalp, or as smooth, circular patches on your head. "Alopecia areata causes discrete, often circular, areas of hair loss," the British Thyroid Foundation explains. "In most cases this is transient and does not progress, but unfortunately it can cause significant baldness."
And it's not just the hair on your head that's affected.
Because the hair growth process is broadly the same across your whole body, thyroid-related hair loss may not be limited to your scalp. In some cases, you may lose hair from other areas like your eyebrows and legs. David Beatty, MRCGP, a general practitioner with more than 30 years of experience, previously told Best Life that most of the eyebrow hair loss from hypothyroidism occurs in the outer third part of your brow.
However, with successful treatment of the underlying condition, any hair loss will be reversed as your thyroid levels return to normal, according to MedicalNewsToday.
There are some other surface symptoms of thyroid disease you should be looking out for.
The thyroid is so integral to your body's regulation that anytime levels are off, it can cause a vast array of issues. Safer's paper warns that there are multiple skin manifestations of thyroid dysfunction, including thin, scaly skin; edema (swelling) to the hands, face, and eyelids; thin or brittle nails; irregular sweating; cold intolerance; heat intolerance; and drooping of the eyelids. Of course, that's in addition to an enlarged goiter at the base of your neck, the tell-tale sign of a thyroid issue.
If any of these symptoms are occurring, your doctor can check your hormone levels and determine the best course of action. Given the wide range of conditions that both hyper- and hypothyroidism can cause, it's essential that you don't delay investigation.