Normally, these hairs are replaced with new ones over time.
Fortunately, most cases of thyroid-related hair loss are temporary and treatable.
Causes
Thyroid diseases occur when the normal production of thyroid hormones is disrupted.

Verywell / Emily Roberts
The key hormones are triiodothyronine (T3) and thyroxine (T4).
Hair growth can be unpredictable and some people grow it back faster than others.
It may take being on thyroid medication for several months before your hair starts to come back in.

Verywell / James Bascara
Also, be aware that the new hair may be a different color or texture.
How can I hide my thyroid disease-related hair loss until it grows back?
Hats, head scarves, and wigs can all help.
You may also be able to style your hair strategically to cover thinning or bald patches.
Be sure to talk to your hairstylist to see if a different cut or style would help.
They may also know of products that can add body or make your hair appear fuller.
What does thyroid disease-related hair loss look like?
How common is it to experience hair loss from thyroid medication?
It’s fairly common to see some hair loss due to thyroid medication.
In most people, this is a short-lived side effect that occurs in the first month of treatment.
In the meantime, give a shot to stave off further hair loss by treating your hair gently.
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