"Terri, I am absolutely shocked! I took my newly turned 18-year old high school senior for some medical tests this past week. The Patient Representative spoke to my son; she did not address me. I then remembered, this is what you were talking about!"
I got this phone call from a friend of mine a couple of weeks ago. Her son has some medical issues and during a recent hospital visit for tests, discovered things had changed; simply because her son turned 18. The medical representatives no longer asked her questions about his medicines and history, they asked her son directly. Her son, being as shocked as she was, was not prepared to take over his own medical decisions.

In my friend's case, there wasn't an emergency. She was accompanying her son for some medical tests, which is often the case in her situation. But this time the difference was, her son is 18.
How can you be prepared?
This realization motivated my friend to action. Her son's medical condition is one he will have his whole life. She and her husband know this and are prepared to help him as long as it takes, but they were unprepared for the privacy issues that come into existence the day their children turn 18. After-all, it's not like we get a notice in the mail as parents alerting us to this fact. She immediately contacted an attorney, and executed the healthcare power of attorney.

There are many things that happen the day your child turns 18 that might catch you off guard. The HIPAA privacy issue is one, a major one. There are a few others that a blogger from About Parenting captured in this article you might find helpful.
Be Aware of How Your Role Changes
"The day your child turns 18 you no longer have access to their medical info"