clarification about privacy

Had some questions about a previous post. Did some homework and here is the answer 

Cancer Tip #14 – Know the laws governing healthcare and privacy. AS a general rule I don’t care who knows what about me, but some people care so make sure you know what’s what. For example I talked to some HR folks and they told me that you can say anything you want about yourself – you can start a blog, a caring bridge site, put up billboards, or have a fundraiser. That self-promotion is NOT implicit approval that you have somehow given up your privacy right. IN order for employers to use your illness information requires explicit approval by you. Simply, you can talk about you all day long – they can’t unless you allow it.