Tubulo-interstitial nephritis, not specified as acute or chronic
In Renal tubulo-interstitial diseases (N10-N16), chapter 14: Diseases of the Genitourinary System
- N12 is billable and valid on claims for FY 2027. If the record has more detail, check the other codes under N10-N16 below.
- As a secondary diagnosis it is a CC (complication or comorbidity), which can raise the MS-DRG payment. It doesn't count when the principal diagnosis is one of 228 closely related codes.
- Doesn't count toward a Medicare Advantage risk score (no HCC in V28).
- AHRQ's Chronic Condition Indicator classes it as not chronic (an acute or short-term condition).
- 955 US deaths in 2024 had an underlying cause in category N12, per the National Vital Statistics System on CDC WONDER. Death records use WHO ICD-10, so the count is for the whole category.
Also indexed as: Disease, antiglomerular basement membrane antibody, tubulo-interstitial nephritis; Disease, renal, with, interstitial nephritis; Nephritis, antitubular basement membrane NEC; Nephritis, tubulo-interstitial; Pyelonephritis, nonobstructive; Pyonephritis
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Instructional notes
Includes: conditions that are coded here
- Interstitial nephritis NOS
- Pyelitis NOS
- Pyelonephritis NOS
Excludes1: not coded here, use a different code
- calculous pyelonephritis (N20.9)
Also applies, from Renal tubulo-interstitial diseases (N10-N16)
These notes sit on N10-N16 and apply to every code under it, including N12.
Includes: conditions that are coded here
- pyelonephritis
Excludes1: not coded here, use a different code
- pyeloureteritis cystica (N28.85)
Official coding guidelines
From the ICD-10-CM Official Guidelines for Coding and Reporting, FY 2027 (CMS and NCHS). Links open the PDF at the right page.
Covers chronic kidney disease staging, CKD in kidney transplant patients, and sequencing CKD with related conditions such as diabetes and hypertension.
- Chronic kidney disease (page 62)
Other codes under N10-N16
Renal tubulo-interstitial diseases (N10-N16)
- N10Acute pyelonephritis
- N11Chronic tubulo-interstitial nephritis
- N12Tubulo-interstitial nephritis, not specified as acute or chronic(this code)
- N13Obstructive and reflux uropathy
- N14Drug- and heavy-metal-induced tubulo-interstitial and tubular conditions
- N15Other renal tubulo-interstitial diseases
- N16Renal tubulo-interstitial disorders in diseases classified elsewhere
N12 MS-DRGs
As the principal diagnosis, N12 groups to MS-DRG 689, 690, 791, or 793 (v44.0). Which one applies depends on procedures performed, secondary diagnoses (CC/MCC), and the patient's age and discharge status.
Related conditions
Grouped by AHRQ's Clinical Classifications Software Refined (CCSR), which sorts every diagnosis code into clinically meaningful categories.
N12 is in Urinary tract infections (GEN004, its default category), with 61 codes. Others in it:
- A02.25 Salmonella pyelonephritis
- A18.10 Tuberculosis of genitourinary system, unspecified
- A18.13 Tuberculosis of other urinary organs
- A36.85 Diphtheritic cystitis
- A52.75 Syphilis of kidney and ureter
- A54.01 Gonococcal cystitis and urethritis, unspecified
- A56.01 Chlamydial cystitis and urethritis
- A59.03 Trichomonal cystitis and urethritis
Medicare coverage articles listing N12
These 2 Medicare billing and coding articles list N12 as a diagnosis that supports medical necessity for the services they cover. From the CMS Medicare Coverage Database; check your own contractor's article before billing.
Other codes that refer to N12
Notes on these codes point to N12.
- N05 Excludes1: tubulo-interstitial nephritis NOS (N12)
About the condition
Plain-language background from MedlinePlus (National Library of Medicine), not coding guidance.
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. It goes to your bladder, which stores the urine until you go to the bathroom.
Read more about kidney diseases on MedlinePlusCode history
Valid since FY2016, when ICD-10-CM took effect on October 1, 2015. No changes since.
ICD-9-CM equivalent
Legacy crosswalk from the CMS General Equivalence Mappings (last updated 2018).
- 590.80 Pyelonephritis, unspecified (approximate)