N10 ICD-10-CM Code: Acute pyelonephritis

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for N10 in the official ICD-10-CM tabular list, quoted as published.

Source: CMS/CDC — ICD-10-CM Tabular ListRelease: FY2026Effective: October 1, 2025

Notes without a marker are published on N10 itself; “inherited from” names the category or block whose note applies here.

Coder workflow for N10

MedCoder structured workflow — derived from this code’s own official record

Before you code N10

1. Check the Excludes1 note: if the documentation supports a condition named there, do not simply proceed with N10. Excludes1 conditions are not reported together with this code unless the record shows they are unrelated (Guidelines I.A.12.a).

   See the official tabular notes

Choose the right path

1. Does the documentation support a condition named in N10’s Excludes1 note?
   Yes → Do not simply proceed: review the excluded code. Both are reported only when the record shows the two conditions are unrelated.
   No → Continue.

   ReviewN28.85

Consider N10. Then work the Use Additional Code note, and confirm the code is valid for the date of service in the Verify section.

Documentation check

The provider’s diagnostic statement

Codes are assigned from the provider’s documented diagnosis, not from clinical criteria, test values or a medication list (Guidelines I.A.19).

Acuity

Acute or chronic as documented; when both are documented and separate codes exist, both are reported with the acute code first (Guidelines I.B.8).

The conditions the Use Additional Code note names

Reported with this code when documented; a conditional instruction (“if applicable”, “if known”) applies only when the record supports it.

Official instructions as workflow

• Excludes1 — check before selecting N10(1 note)

  Coding workflow: If the documentation supports a condition named in this note, do not simply proceed with N10: the two are not reported together. The one exception is when the record shows the two conditions are unrelated to each other.

  CompareN28.85

  See the official tabular notes · Guidelines I.A.12.a

• Use Additional Code — after identifying N10(1 note)

  Coding workflow: Check whether the documentation supports the additional code(s) the note names, and report them with N10 when it does. Where the instruction is conditional (“if applicable”, “if known”), it applies only when the record documents the condition.

  See the official tabular notes · Guidelines I.A.13

Coding decision scenarios

Pattern scenarios for this code’s structure — decision rules, not clinical cases

Every row is derived from this code’s own record — its title, tabular notes, 7th-character family and same-category siblings — with fixed MedCoder wording; nothing is inferred about a patient. The official notes and guideline text are in the sections each row links to, and they control.

Indexed Clinical Terms (5)

Official source data — entries quoted as published, in the Index’s own lookup phrasing

Clinical term phrases from the official ICD-10-CM Index to Diseases and Injuries that map to this code. These are alphabetic-index entries shown as the Index writes them — lookup phrasing, not necessarily the wording of a final diagnosis.

• Nephritis, nephritic (albuminuric) (azotemic) (congenital) (disseminated) (epithelial) (familial) (focal) (granulomatous) (hemorrhagic) (infantile) (nonsuppurative, excretory) (uremic), tubulo-interstitial (in), acute (infectious)
• Nephrosis, nephrotic (Epstein's) (syndrome) (congenital), hemoglobin
• Nephrosis, nephrotic (Epstein's) (syndrome) (congenital), myoglobin
• Pyelitis (congenital) (uremic), acute
• Pyelonephritis, acute

Don’t confuse N10 with…

MedCoder analysis — pairs from this code’s official notes, distinctions written by MedCoder

The codes most likely to be picked instead of N10 — named in its own official notes, or sharing its laterality or encounter family — with what separates them and which documentation moves the case. Each links to the full comparison.

• N28.85— Excludes1 conflict (Excludes1 — generally not reported together)

  Not coded here — the tabular list excludes this pair for the same encounter.

  Not reported together with this code, except where the two conditions are documented as unrelated.

  What moves you there: Documentation of pyeloureteritis cystica moves the case to N28.85; the two are not reported together unless documented as unrelated.

  Full comparison: N10 vs N28.85 →

Relationships are read from this code's own official notes, its laterality siblings and its encounter family; the wording of each distinction is MedCoder editorial, and the documentation named in each “what moves you there” line is the official note phrase or sibling title itself. Source: CMS ICD-10-CM tabular instructional notes; ICD-10-CM Official Guidelines, Section I.A.12.a.

Verify Before Coding

• CC as a secondary diagnosis (FY2026). Can raise the stay's MS-DRG severity tier.

From the code registry, the Medicare Code Editor, and the MS-DRG Definitions Manual. Check it against a full claim in Claim Check.

Relationships & Classification

MedCoder structured relationships — computed from published CMS and AHRQ datasets

Other codes that name N10 or its code family, from the CMS ICD-10-CM tabular instructional notes. Tabular-note edges are stored at the code family level that carries each note.

Referenced by 1 Excludes1 note: N00 — Acute nephritic syndrome.

These codes’ tabular lists mark this diagnosis as mutually exclusive — not reported together unless the conditions are documented as unrelated.

MS-DRG Grouper Relationships (FY2026)

Potential MS-DRG participation — not a DRG assignment.

FY2026 MS-DRG: CC — Complication or Comorbidity. Reported as a secondary diagnosis, this code raises the stay's MS-DRG severity tier — except when the principal diagnosis is one of 279 clinically related codes on its CMS exclusion list.

Named in the grouper logic of 4 MS-DRGs: DRG 689 (MDC 11), DRG 690 (MDC 11), DRG 791 (MDC 15), DRG 793 (MDC 15).

From the CMS MS-DRG Definitions Manual (Appendices B and C). Actual DRG assignment depends on the complete claim.

Clinical classification (AHRQ CCSR):GEN004 — Urinary tract infections (default).

Clinical Classifications Software Refined (CCSR) for ICD-10-CM Diagnoses. Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality.

Related Codes

Same clinical process (MS-DRG)

Acts as CC — raises the severity of other admissions. CMS groups these diagnoses into one MS-DRG principal-diagnosis exclusion process — a CC/MCC on this list never raises severity when the principal diagnosis is also on it.

N07.1 — Hereditary nephropathy, not elsewhere classified with focal and segmental glomerular lesions, N07.2 — Hereditary nephropathy, not elsewhere classified with diffuse membranous glomerulonephritis, N07.3 — Hereditary nephropathy, not elsewhere classified with diffuse mesangial proliferative glomerulonephritis, N07.4 — Hereditary nephropathy, not elsewhere classified with diffuse endocapillary proliferative glomerulonephritis, N07.5 — Hereditary nephropathy, not elsewhere classified with diffuse mesangiocapillary glomerulonephritis, N07.6 — Hereditary nephropathy, not elsewhere classified with dense deposit disease, N07.7 — Hereditary nephropathy, not elsewhere classified with diffuse crescentic glomerulonephritis, N07.8 — Hereditary nephropathy, not elsewhere classified with other morphologic lesions, N07.9 — Hereditary nephropathy, not elsewhere classified with unspecified morphologic lesions, N07.B — Hereditary nephropathy, not elsewhere classified with APOL1-mediated kidney disease [AMKD], N11.0 — Nonobstructive reflux-associated chronic pyelonephritis, N11.8 — Other chronic tubulo-interstitial nephritis, N11.9 — Chronic tubulo-interstitial nephritis, unspecified, N12 — Tubulo-interstitial nephritis, not specified as acute or chronic, N13.0 — Hydronephrosis with ureteropelvic junction obstruction, N13.1 — Hydronephrosis with ureteral stricture, not elsewhere classified, N13.2 — Hydronephrosis with renal and ureteral calculous obstruction, N13.30 — Unspecified hydronephrosis, N13.39 — Other hydronephrosis, N13.6 — Pyonephrosis, +258 more

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical category (Urinary tract infections).

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, B37.41 — Candidal cystitis and urethritis, B37.49 — Other urogenital candidiasis, N11.0 — Nonobstructive reflux-associated chronic pyelonephritis, N11.1 — Chronic obstructive pyelonephritis, N11.8 — Other chronic tubulo-interstitial nephritis, N11.9 — Chronic tubulo-interstitial nephritis, unspecified, N12 — Tubulo-interstitial nephritis, not specified as acute or chronic, N13.6 — Pyonephrosis, N15.1 — Renal and perinephric abscess, N30.00 — Acute cystitis without hematuria, N30.01 — Acute cystitis with hematuria, N30.10 — Interstitial cystitis (chronic) without hematuria, +40 more

Same Index main term, other category

The ICD-10-CM Index to Diseases and Injuries files this code under the main terms “Pyelonephritis”, “Pyelitis”, “Nephritis, nephritic”, …; these codes share that main term but sit in a different category of the Tabular List.

N05.1 — Unspecified nephritic syndrome with focal and segmental glomerular lesions (with, focal and segmental glomerular lesions), N05.2 — Unspecified nephritic syndrome with diffuse membranous glomerulonephritis (with, diffuse, membranous glomerulonephritis), N05.3 — Unspecified nephritic syndrome with diffuse mesangial proliferative glomerulonephritis (with, diffuse, mesangial proliferative glomerulonephritis), N05.4 — Unspecified nephritic syndrome with diffuse endocapillary proliferative glomerulonephritis (with, diffuse, endocapillary proliferative glomerulonephritis), N05.5 — Unspecified nephritic syndrome with diffuse mesangiocapillary glomerulonephritis (membranoproliferative), N05.6 — Unspecified nephritic syndrome with dense deposit disease (with, dense deposit disease), N05.7 — Unspecified nephritic syndrome with diffuse crescentic glomerulonephritis (with, diffuse, crescentic glomerulonephritis), N05.8 — Unspecified nephritic syndrome with other morphologic changes (proliferative NEC), N05.9 — Unspecified nephritic syndrome with unspecified morphologic changes, N05.A — Unspecified nephritic syndrome with C3 glomerulonephritis (with, C3, glomerulopathy), N11.0 — Nonobstructive reflux-associated chronic pyelonephritis (nonobstructive, with reflux), N11.1 — Chronic obstructive pyelonephritis (in, obstruction), N11.8 — Other chronic tubulo-interstitial nephritis (chronic, specified NEC), N11.9 — Chronic tubulo-interstitial nephritis, unspecified (chronic), N12 — Tubulo-interstitial nephritis, not specified as acute or chronic (nonobstructive), N13.6 — Pyonephrosis (with, calculus, with hydronephrosis), N14.3 — Nephropathy induced by heavy metals (lead), N15.0 — Balkan nephropathy (Balkan), N17.0 — Acute kidney failure with tubular necrosis (tubular), N25.89 — Other disorders resulting from impaired renal tubular function (osmotic), +81 more

Lab tests where this diagnosis supports Medicare coverage (NCD)

Medicare's National Coverage Determination (NCD) program lists this diagnosis as medical justification for these lab tests.

Blood Glucose Test, Gamma-glutamyl Transferase (GGT) Test

Contextual Map

Every relationship of N10 in one view: hierarchy, official tabular instructions in both directions, clinical classification, risk adjustment, MS-DRG participation, index terms and change history — each edge carrying the CMS source it derives from.

Run N10 with these 5 related codes in Claim Check

Hierarchy

• N00-N99 — Chapter 14: Diseases of the Genitourinary System (N00-N99) (N00-N99)[Hierarchy]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• N10-N16 — Renal tubulo-interstitial diseases[Hierarchy]— CMS ICD-10-CM tabular structure · icd10cm-fy2026

Excludes1

• N28.85 — Pyeloureteritis cystica[Excludes1]: “pyeloureteritis cystica (N28.85)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026

Use Additional Code

• B95 — Streptococcus, Staphylococcus, and Enterococcus as the cause of diseases classified elsewhere[Use Additional Code]: “code (B95-B97), to identify infectious agent.”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• B96 — Other bacterial agents as the cause of diseases classified elsewhere[Use Additional Code]: “code (B95-B97), to identify infectious agent.”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• B97 — Viral agents as the cause of diseases classified elsewhere[Use Additional Code]: “code (B95-B97), to identify infectious agent.”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026

Referenced by Excludes1 notes

• N00 — Acute nephritic syndrome[Excludes1]: “acute tubulo-interstitial nephritis (N10)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026

Clinical classification (CCSR)

• GEN004 — Urinary tract infections[CCSR]— AHRQ CCSR for ICD-10-CM Diagnoses (HCUP)

MS-DRG Grouper

• CC — Complication or Comorbidity [MS-DRG severity]: “As a secondary diagnosis this code can raise the stay's MS-DRG severity tier (CC).”— CMS MS-DRG Definitions Manual (Appendix C) · FY2026
• DRG 689 — KIDNEY AND URINARY TRACT INFECTIONS WITH MCC[MS-DRG]: “KIDNEY AND URINARY TRACT INFECTIONS WITH MCC (MDC 11)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 690 — KIDNEY AND URINARY TRACT INFECTIONS WITHOUT MCC[MS-DRG]: “KIDNEY AND URINARY TRACT INFECTIONS WITHOUT MCC (MDC 11)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 791 — PREMATURITY WITH MAJOR PROBLEMS[MS-DRG]: “PREMATURITY WITH MAJOR PROBLEMS (MDC 15)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 793 — FULL TERM NEONATE WITH MAJOR PROBLEMS[MS-DRG]: “FULL TERM NEONATE WITH MAJOR PROBLEMS (MDC 15)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026

MDC crossing

• MDC 11 — Diseases and Disorders of the Kidney and Urinary Tract[MDC crossing]: “Diseases and Disorders of the Kidney and Urinary Tract — the grouper's crossing between diagnoses and procedures: a principal diagnosis sets the MDC, and same-MDC procedures move the stay to its surgical DRGs. 3,574 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2026
• MDC 15 — Newborns and Other Neonates with Conditions Originating in Perinatal Period[MDC crossing]: “Newborns and Other Neonates with Conditions Originating in Perinatal Period — the grouper's crossing between diagnoses and procedures: a principal diagnosis sets the MDC, and same-MDC procedures move the stay to its surgical DRGs.”— CMS MS-DRG Definitions Manual · FY2026

Index entries

• Nephritis, nephritic (albuminuric) (azotemic) (congenital) (disseminated) (epithelial) (familial) (focal) (granulomatous) (hemorrhagic) (infantile) (nonsuppurative, excretory) (uremic), tubulo-interstitial (in), acute (infectious)[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
• Nephrosis, nephrotic (Epstein's) (syndrome) (congenital), hemoglobin[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
• Nephrosis, nephrotic (Epstein's) (syndrome) (congenital), myoglobin[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
• Pyelitis (congenital) (uremic), acute[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
• Pyelonephritis, acute[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026

Change history (3)

• FY2017 — Description revised[Change history]— CMS release files (code change ledger) · icd10cm-fy2017
• and 2 more

Sources for this page

Codes, titles, notes, index terms and mappings on this page are transcribed from the datasets below. Relationships MedCoder computed and text MedCoder wrote are labelled where they appear.

Code, title, tabular notes and index terms Official source data

CMS/CDC ICD-10-CM FY2026 tabular list, index and tables, effective October 1, 2025 Release, file and checksum · Publisher’s page

Claim edits Official source data

CMS Definitions of Medicare Code Edits — v43.1 (April 2026) Release, file and checksum · Publisher’s page

Inpatient payment groups Official source data

CMS MS-DRG Definitions Manual (incl. Appendix B diagnosis index, Appendix C CC/MCC list, Appendix E procedure index) and IPPS Final Rule tables — v43 Release, file and checksum · Publisher’s page

Change history and date-of-service validity Official source data

CMS ICD-10-CM release addenda, ingested release by release into the change ledger Release, file and checksum · Publisher’s page

Comparisons, relationships and the contextual map MedCoder structured relationship

Computed by MedCoder from the tabular notes and tables above; every derived relationship is marked as derived where it appears

Summary and FAQ answers MedCoder explanation

Written by MedCoder to explain the sources above: drafted with AI assistance, checked by a person against the release files, and labelled as MedCoder text where it appears. Not official text.

Labels on this page: Official source data · MedCoder structured relationship · MedCoder explanation. How to read the labels · All data sources and release dates