HIPPA gives rules to protect your helath information.
Below is from the HIPPA website:
Requests from your employer
The Privacy Rule does not prevent your supervisor, human resources worker or others from asking you for a doctor’s note or other information about your health if your employer needs the information to administer sick leave, workers’ compensation, wellness programs, or health insurance.
•However, if your employer asks your health care provider directly for information about you, your provider cannot disclose the information in response without your authorization.
•Covered health care providers must have your authorization to disclose this information to your employer, unless other laws require them to disclose it.
From a management perspective, I would need to know what duties you are and aren't able to perform. This proects the organization I work for because I don't want to give you assignments that your physicians don't feel your are capapable of performing, could worsen our symptoms, or cause you harm.
Your doctors can provide your employers with your limitations (ex. no lifting over 10 pounds, no bending or twisting, etc...) without actually giving your employer your medical diagnosis.
Disclaimer: I am not a lawyer nor am I offering any legal or medical advice. I am only providing my opinion for your consumption.