What can cause a 58 year old woman's hair to fall out in big oval patches bigger then a 50 cent piece?

Thank you Susan for your comments.

Hello Anon
Thank you for writing.
Please have your hormones checked - a full panel that includes your reproductive hormones as well as your thyroid. Both of these types can cause hair loss, especially in the 40-60 age bracket.
If your results are fine, see a dermatologist.
I hope you get to the bottom of this.
Best,
Susan