The answer is "actual expenses on a case by case basis." This is directly from the Arizona Chapter 13 Trustees. I've included the document in a link.
You may have been confused by the two entries of this expenses that you must complete.
The 1st time you enter this information is in Schedule J “Expenses”
The 2nd time you enter this information is in the Means Test, B 22-A. This itemization includes provision for standard deduction of approximately $60 per person, but allows additional cost above the base amount.
If the expenses are much larger than standard IRS deductions or average for your district, then you may have to show the trustee why you're entitled to a large medical expense.