What ethical concerns do you have about the sharing of health data online?

Electronic health records have become the gold standard in improving the quality of care and provision of cost effective healthcare. However, even as sharing health information online harbors numerous advantages, its use raises a range of ethical concerns. My major concern is the possible breach of autonomy, whereby my information may be shared with other users without my consent. Privacy is another concern attributable to the increased ease of re-identification, efficient data mining, and hacking or accidental security breaches. What otehr ethical concerns can you think about, top of the hat?