2026 ICD-10-CM Diagnosis Code M13.80Other specified arthritis, unspecified site

ICD-10-CM Codes›M00–M99›M05-M14›M13

ICD-10-CM M13.80
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

M13.80 is a billable ICD-10-CM diagnosis code for other specified arthritis, unspecified site. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 553 through 554. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other specified joint disorders.

Code Identity

ICD-10-CM Code
M13.80
Billable Status
Yes — Valid for Submission
Code Describes
Other specified arthritis, unspecified site
Short Description
Other specified arthritis, unspecified site
Same as the full description in the CMS dataset.
Parent Code
M13.8
Other specified arthritis

Code Classification

ChapterM00–M99Diseases of the musculoskeletal system and connective tissue
SectionM05-M14Inflammatory polyarthropathies
CategoryM13Other arthritis
This CodeM13.80Other specified arthritis, unspecified site

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Acute arthritis
  • Allergic arthritis
  • Arthritis due to alkaptonuria
  • Arthritis secondary to amyloidosis
  • Arthropathy associated with a hypersensitivity reaction
  • Asymmetrical arthritis
  • Chronic arthritis
  • Climacteric arthritis
  • Degenerative polyarthritis
  • Generalized arthritis
  • Immune dysregulation, inflammatory bowel disease, arthritis, recurrent infection syndrome
  • Interstitial granulomatous dermatitis with arthritis
  • Large joint arthritis
  • Ochronotic arthritis
  • Pseudoparalysis
  • Pseudoparalysis due to generalized arthritis
  • Secondary inflammatory arthritis
  • Small joint arthritis
  • Subacute arthritis
  • Subacute arthropathy
  • Symmetrical arthritis
  • Transient arthritis
  • Undifferentiated inflammatory arthritis
  • Villous arthritis

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Arthritis, arthritic(acute) (chronic) (nonpyogenic) (subacute)
      • specified form NEC

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR MUS007
Other specified joint disorders
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Allergic Arthritis

    arthritis occurring after the ingestion of allergenic substance(s).

  • Climacteric Arthritis

    arthritis that occurs during menopause.

Patient EducationClinical

Arthritis

If you feel pain and stiffness in your body or have trouble moving around, you might have arthritis. Any disorder that affects the joints is often called arthritis. Joints are places where two bones meet, such as your elbow or knee.

The full article covers:

  • What is arthritis?
  • What are the types of arthritis?
  • What are the symptoms of arthritis?
  • Who is more likely to get arthritis?
  • How is arthritis diagnosed?
  • What are the treatments for arthritis?

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert M13.80 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
716.20 Allerg arthritis-unspec
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About M13.80Overview

Is M13.80 (Other specified arthritis) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report other specified arthritis, unspecified site on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does M13.80 group to?

When other specified arthritis, unspecified site is the principal diagnosis on an inpatient stay, it groups to MS-DRG 553, 554, with relative weights from 0.8301 to 1.2963 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of M13.80?

Under the General Equivalence Mappings, other specified arthritis, unspecified site converts to ICD-9-CM 716.20 (allerg arthritis-unspec). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.