The horse is out of the barn on this one. Be sure to read what you sign next time. In the meantime, I can only speak for myself when I say that I would not take your case to suit.
Sounds like a semantics event. Is your therapist a doctor? Does your doctor think that your therapist is a doctor? Did your therapist get the info directly from the doctor?
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Health care providers have very great latitude under HIPAA and other medical privacy laws to share information for the purpose of caring for patients. If you don't want this to happen again, be VERY clear up front about your expectations and prepared to find another doctor if he / she takes a different view.
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