When you're talking about someone at work with a higher position than you who you sometimes speak to, it's usually normal to use their first name. For example, if you say "Hi" and make small talk with the Vice President of your division once a month, it's probably OK to refer to her by her first name:
Have you submitted this to Jason for approval yet?
If you've never spoken with someone, and they're much higher up in the organization than you, you might call them by their full name instead:
I saw Jason Kaplan in the elevator this morning. He seemed to be in a good mood.
Of course, this depends on the company and the culture. The rules above are for corporate jobs in the U.S. It might be different internationally or for some jobs like university professors.