2027 ICD-10-CM Diagnosis Code N12Tubulo-interstitial nephritis, not specified as acute or chronic
ICD-10-CM Codes›N00–N99›N10-N16›N12
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Not Chronic
N12 is a billable ICD-10-CM diagnosis code for tubulo-interstitial nephritis, not specified as acute or chronic. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 689 through 690, 791, 793. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 228 closely related codes. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Urinary tract infections.
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Anti-glomerular basement membrane disease
- Anti-glomerular basement membrane tubulointerstitial nephritis
- Diffuse pyelonephritis
- Familial interstitial nephritis
- Granulomatous tubulointerstitial nephritis
- Idiopathic granulomatous interstitial nephropathy
- Idiopathic interstitial tubulonephritis
- Immunologic mediated TIN
- Mycoplasmal pyelonephritis
- Primary tubulointerstitial nephritis
- Pyelitis
- Pyelonephritis
- Recurrent pyelonephritis
- Recurrent urinary tract infection
- Secondary tubulointerstitial nephritis
- Subacute pyelonephritis
- Tubulointerstitial nephritis
- Tubulointerstitial nephritis with uveitis syndrome
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to N12: its own notes plus those printed at block N10-N16 and Chapter 14. A note printed at a category, block or chapter applies to every code under it.
Applicable To
Conditions this code is used for: synonyms of the title or, for "other specified" codes, the conditions assigned to it. The list is not exhaustive.
- Interstitial nephritis NOS
- Pyelitis NOS
- Pyelonephritis NOS
Excludes1
Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.
- calculous pyelonephritis (N20.9)
- pyeloureteritis cystica (N28.85)
Excludes2
Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may 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)
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name N12, its category, or a range that includes it.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Disease, diseased See Also: Syndrome;
renal (functional) (pelvis) See Also: Disease, kidney; N28.9
Nephritis, nephritic (albuminuric) (azotemic) (congenital) (disseminated) (epithelial) (familial) (focal) (granulomatous) (hemorrhagic) (infantile) (nonsuppurative, excretory) (uremic) N05.9
Pyelonephritis See Also: Nephritis, tubulo-interstitial;
nonobstructive N12
Pyonephritis N12
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Patient EducationClinical
Kidney Diseases
You have two kidneys, each about the size of your fist. They are near the middle of your back, just below the rib cage. Inside each kidney there are about a million tiny structures called nephrons. They filter your blood. They remove wastes and extra water, which become urine. The urine flows through tubes called ureters.
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert N12 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About N12Overview
What is the ICD-10 code for tubulo-interstitial nephritis, not specified as acute or chronic?
The ICD-10-CM code for tubulo-interstitial nephritis, not specified as acute or chronic is N12. It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is N12 a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report tubulo-interstitial nephritis, not specified as acute or chronic on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does N12 group to?
When tubulo-interstitial nephritis, not specified as acute or chronic is the principal diagnosis on an inpatient stay, it groups to MS-DRG 793, 791, 689, 690, with relative weights from 0.8008 to 4.2192 depending on complications. Higher weights mean higher Medicare reimbursement.
Is N12 a CC or MCC?
CMS lists N12 as a CC (complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 228 closely related codes in its exclusion list.
Can N12 be reported with N20.9?
Not as a rule. The Excludes1 note on N12 lists "calculous pyelonephritis (N20.9)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).
