Hypothyroidism (an under-active thyroid) and the side effects of its related medications can cause hair loss, typically frontal, which is particularly associated with thinning of the outer third of the eyebrows (also seen with syphilis). Hyperthyroidism (an over-active thyroid) can also cause hair loss, which is parietal rather than frontal.[23][unreliable medical source?]
Again, you’ll want to visit your doctor to get a blood test to check your levels in these vitamins. For example, women who have iron levels lower than 70 nanograms per milliliter are considered deficient. From there, work with your doctor to find an appropriate dose according to your deficiency level. Excessive or unnecessary supplementation can be dangerous.

As a senior writer for Live Science, Laura Geggel covers general science, including the environment and amazing animals. She has written for The New York Times, Scholastic, Popular Science and Spectrum, a site covering autism research. Laura grew up in Seattle and studied English literature and psychology at Washington University in St. Louis before completing her graduate degree in science writing at NYU. When not writing, you'll find Laura playing Ultimate Frisbee. Follow Laura on Google+. 


See a doctor. While it may be easy to treat hair loss that's caused by stress or other physical or emotional shock, other types, especially those caused by medical conditions, require expert attention. Do not self-medicate. A medical test is necessary to determine the real cause of your hair loss. A medical diagnosis is important in order to rule out other factors that might be the cause of your hair loss. On the surface, it's easy to attribute hair loss to stress or the lack of sleep, but it is highly possible that the hair loss may be caused by an unknown or undetected condition related to hormones or genetics. With the right diagnosis, you'll be able to get the right medication and course of treatment.
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