A plan for the government to share more health information with researchers might deter privacy-conscious patients from seeking medical treatment, the AMA says.

In August, psychiatrists raised concerns about the use of health data after 50,000 patients received letters inviting them to join a study on bipolar disorder.

The patients were targeted because PBS data showed they were prescribed lithium, but psychiatrists reported that some feared their confidentiality had been broken by their treating doctors.

Now, the AMA has warned these incidents could become more common under reforms being considered by the Federal Government.