You're sharing someone's sensitive data without permission. On top of that, patient data has additional protections in many countries. You can get into legal troubles because of that.
Major providers like Azure or AWS have programs in place to handle sensitive patient data. I'm not sure if OpenAI has one too. Either way, you would have to enter into a special agreement to do so.
Bonus point: ask ChatGPT if it's ok to paste private patient data there.
Don't paste actual patient data.