| N11 | Chronic tubulo-interstitial nephritis | NON-BILLABLE CODE |
| N11.0 | Nonobstructive reflux-associated chronic pyelonephritis | BILLABLE CODE |
| N11.1 | Chronic obstructive pyelonephritis | BILLABLE CODE |
| N11.9 | Chronic tubulo-interstitial nephritis, unspecified | BILLABLE CODE |
