10. Hair Loss
Hair follicles, like most cells, are regulated by thyroid hormone. Hair loss may occur with both hypothyroidism and hyperthyroidism because normal production of the hormones T3 and T4 is disrupted.
When this occurs, your natural hair loss (about 50-100 strands per day) is no longer replaced by fresh growth. The result is thinner hair overall, rather than noticeable bald patches. You may also notice it in your eyebrows and eyelashes.