Gladwin missed the midweek defeat at Barnsley and is also unavailable for this weekend’s home game against Preston.
Rangers expected a prognosis earlier this week but the affected ankle is still badly swollen.
The club must wait for the swelling to go down before scans can confirm how long the midfielder is likely to be sidelined for.
The R’s will also be without Grant Hall on Saturday as he is suspended after being sent off at Barnsley.
This post was last modified on 20/08/2016