N12 — Tubulo-interstitial nephritis, not specified as acute or chronic
Is N12 billable?
Yes — N12 is billable for FY2027. N12 is a valid, billable ICD-10-CM code at the highest level of specificity in its branch. N12 may be submitted for encounters from October 1, 2026 through September 30, 2027.
N12 at a glance
| Code | N12 |
|---|---|
| Description | Tubulo-interstitial nephritis, not specified as acute or chronic |
| Billable | Yes |
| Code set | ICD-10-CM FY2027 |
| Valid for encounters | October 1, 2026 – September 30, 2027 |
Which MS-DRGs does N12 group to?
N12 sits in MDC 11 and helps define the logic of 2 MS-DRGs (version 44, FY2027). Which one a stay actually groups to also depends on procedures and secondary diagnoses.
- 689Kidney and Urinary Tract Infections with MCCmedical
- 690Kidney and Urinary Tract Infections without MCCmedical
As a secondary diagnosis, N12 is a complication or comorbidity (CC), which can move a stay into a higher-paying DRG. It also carries Hospital-Acquired Condition category 06.
How is N12 listed in the Alphabetic Index?
These are the routes through the Alphabetic Index that lead to N12. They show the wording a clinician may have documented, which often differs from the Tabular description.
- Pyonephritis
- Nephritis, nephritic › antitubular basement membraneNEC (albuminuric) (azotemic) (congenital) (disseminated) (epithelial) (familial) (focal) (granulomatous) (hemorrhagic) (infantile) (nonsuppurative, excretory) (uremic)
- Nephritis, nephritic › tubulo-interstitial (albuminuric) (azotemic) (congenital) (disseminated) (epithelial) (familial) (focal) (granulomatous) (hemorrhagic) (infantile) (nonsuppurative, excretory) (uremic)
- Pyelonephritis › nonobstructive
- Disease, diseased › antiglomerular basement membraneantibody › tubulo-interstitial nephritis
- Disease, diseased › renal › with › interstitial nephritis
Excludes1 — never code together
The conditions below can never be reported together with N12 on the same claim. An Excludes1 note means the two conditions cannot occur in the same patient, so reporting both is a coding error.
- calculous pyelonephritis (N20.9)
Inclusion terms
Alternative wording in documentation that is classified to N12.
- Interstitial nephritis NOS
- Pyelitis NOS
- Pyelonephritis NOS
Excludes1 — never code together — inherited from N10-N16
The conditions below can never be reported together with N12 on the same claim. An Excludes1 note means the two conditions cannot occur in the same patient, so reporting both is a coding error.
- pyeloureteritis cystica (N28.85)
Excludes2 — not included here — inherited from Chapter 14
The conditions below are not part of N12, but a patient may have both at the same time. When documentation supports it, N12 and the excluded code may both be reported.
- certain conditions originating in the perinatal period (P04-P96)
- certain infectious and parasitic diseases (A00-B99)
- complications of pregnancy, childbirth and the puerperium (O00-O9A)
- congenital malformations, deformations and chromosomal abnormalities (Q00-Q99)
- endocrine, nutritional and metabolic diseases (E00-E88)
- injury, poisoning and certain other consequences of external causes (S00-T88)
- neoplasms (C00-D49)
- symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)
How long has N12 existed?
N12 has been in ICD-10-CM since at least FY2016, the earliest fiscal year on record here.
Derived from the official order files for FY2016–FY2026. FY2017 and FY2020 publish no order file, so those years are not covered.
Which codes are confused with N12?
ICD-10-CM declares these codes mutually exclusive with N12 — exactly one of each pair can be correct for a given encounter.