Appending Zeros to a number

I need to append zeros to the front of a Dr. number, when that number is less than 5 digits.

I have some code that I use to strip zeros in my translation (see below)

set inp [lindex $xlateInVals 0]

set xlateOutVals [string trimleft $inp 0]

But, I need some that will add zeros until the total number of digits in the number equal 5.  Does anyone have anything that they can share?

Thanks