ICD-10-CM 2027
ICD-10 code for chronic pyelonephritis
Chronic tubulo-interstitial nephritis, unspecified
From the official ICD-10-CM alphabetic index entry “Pyelonephritis › chronic”. Page updated September 29, 2026.
About coding chronic pyelonephritis
The ICD-10-CM code for chronic pyelonephritis is N11.9 (Chronic tubulo-interstitial nephritis, unspecified). The official index lists 6 more specific codes, so check the documentation for details such as type, cause, site or severity before settling on N11.9.
Within N11, choose N11.9 (unspecified) only when documentation doesn't support a more specific option: nonobstructive reflux-associated chronic pyelonephritis (N11.0), chronic obstructive pyelonephritis (N11.1) and other chronic tubulo-interstitial nephritis (N11.8).
Use an additional code (B95-B97), to identify infectious agent.
As a secondary diagnosis it is a CC (complication or comorbidity), which can move an inpatient stay into the "with CC" MS-DRG of its family, unless the principal diagnosis excludes it.
More specific chronic pyelonephritis codes (official index)
- with calculus
- with hydronephrosis N13.6 — Pyonephrosis
- associated with ureteral obstruction or stricture N11.1 — Chronic obstructive pyelonephritis
- nonobstructive N11.8 — Other chronic tubulo-interstitial nephritis
- with reflux (vesicoureteral) N11.0 — Nonobstructive reflux-associated chronic pyelonephritis
- obstructive N11.1 — Chronic obstructive pyelonephritis
- specified NEC N11.8 — Other chronic tubulo-interstitial nephritis
Common questions about chronic pyelonephritis ICD-10 codes
What is the ICD-10 code for chronic pyelonephritis?
- N11.9 — Chronic tubulo-interstitial nephritis, unspecified. More specific codes apply when the documentation supports them: N13.6, N11.1, N11.8, N11.0 and others below.
What is the ICD-10 code for nonobstructive chronic pyelonephritis?
- N11.8 — Other chronic tubulo-interstitial nephritis.
What is the ICD-10 code for obstructive chronic pyelonephritis?
- N11.1 — Chronic obstructive pyelonephritis.
Is N11.9 billable?
- Yes. N11.9 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can N11.9 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict N11.9 as a principal diagnosis.
Is N11.9 a CC or MCC?
- N11.9 is a CC (complication or comorbidity) under MS-DRG v44.0, unless excluded by the principal diagnosis.