Check number of users on terminal server, with preformance d

In our enviromnet we have a number of terminal servers, and we check the number of active users with the check_nt plugin and the “Active Sessions” counter on the windows server. The problem is that we’re not geting any preformance data from that check. The output is just numbers, but still no preformance data.
Is there a known way to check active users and get preformance data with check_nt, or do i need to script a new “plugin” that simply runs the same check_nt but outputs preformancedata as well?