Using schema.org microdata for Database Content

Hi,
 
I was wondering if one should mark html text fields with schema.org microdata for fields which will contain values (of known type) retrieved from a database, but which are initially empty upon loading the web page (and thus empty for Search Engines). Basically, I have some fields that I would like to mark using microdata, which will not contain any data until the values are retrieved from a database, the population of which would be initiated by users.
 
Are there any risks for Search Engines to “penalize” a Web Site having microdata for fields which are not yet populated? From my understanding of the schema.org specifications, a Web Site can be “penalized” when marking content which is not visible to users. Is this rule applicable to fields which have not yet been populated (although its content is known)? Does the schema.org specifications take into account this situation? I would like to avoid having my Web Site erroneously penalized.
 
Thank you for your time.
 
Regards,
 
JF