2027 ICD-10-CM Diagnosis Code G13.2Systemic atrophy primarily affecting the central nervous system in myxedema

ICD-10-CM Codes›G00–G99›G10-G14›G13

ICD-10-CM G13.2
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

G13.2 is a billable ICD-10-CM diagnosis code for systemic atrophy primarily affecting the central nervous system in myxedema. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 56 through 57. The code is a manifestation code that cannot be reported as the principal diagnosis. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other nervous system disorders (neither hereditary nor degenerative).

G13.2 no longer risk-adjusts for Medicare Advantage: it mapped to HCC 52 under the retired CMS-HCC V24 model through payment year 2025 but maps to no category in the live V28 model. It still risk-adjusts in the ESRD (V21) category 52, ESRD (V24) category 52, and RxHCC Part D (V08) category 112 for payment year 2027.

Code Identity

ICD-10-CM Code
G13.2
Billable Status
Yes — Valid for Submission
Code Describes
Systemic atrophy primarily affecting the central nervous system in myxedema
Short Description
Systemic atrophy primarily affecting the cnsl in myxedema
Parent Code
G13
Systemic atrophies primarily affecting central nervous system in diseases classified elsewhere

Code Classification

ChapterG00–G99Diseases of the nervous system
SectionG10-G14Systemic atrophies primarily affecting the central nervous system
CategoryG13Systemic atrophies primarily affecting central nervous system in diseases classified elsewhere
This CodeG13.2Systemic atrophy primarily affecting the central nervous system in myxedema

Code EditsBilling

Medicare Code Editor checks that affect claim validity for G13.2.

Manifestation diagnoses
Manifestation codes describe the manifestation of an underlying disease, not the disease itself, and therefore should not be used as a principal diagnosis.

Medicare Risk Adjustment (HCC)Billing

G13.2 no longer risk-adjusts for Medicare Advantage: it maps to no payment category in the live CMS-HCC V28 model, although it still risk-adjusts in the other CMS models shown below.

CMS-HCC V28 (Medicare Advantage Payment Model)
Not mapped
Dropped in V28 see all codes that no longer risk-adjust
Prior Model (CMS-HCC V24)
HCC 52
V24 retired last contributed to a Medicare Advantage risk score in payment year 2025
Other CMS Models
ESRD (V21): HCC 52 · ESRD (V24): HCC 52
ESRD V21 weights: 0.045 dialysis, 0.000–0.328 functioning graft · ESRD V24 weights: 0.042 dialysis, 0.000–0.399 functioning graft
Part D (RxHCC)
RxHCC 112 — Dementia, Except Alzheimer's Disease
also risk-adjusts in the Part D prescription drug model (V08)

Source: CMS Payment Year 2027 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to G13.2: its own notes plus those printed at Chapter 6. A note printed at a category, block or chapter applies to every code under it.

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.

From Chapter 6 (G00-G99) Diseases of the nervous system applies to 700 codes
  • 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)

Code First

The underlying condition named in the note is sequenced before this code.

  • underlying disease, such as:
  • hypothyroidism (E03.-)
  • myxedematous congenital iodine deficiency (E00.1)

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name G13.2, its category, or a range that includes it.

Excludes1 1

These codes carry an Excludes1 note naming G13.2: they are not reported together with it, unless the two conditions are unrelated.

  • G32.81 Cerebellar ataxia in diseases classified elsewhere
    systemic atrophy primarily affecting the central nervous system in myxedema (G13.2)

Clinical ClassificationClinical

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

CCSR NVS020
Other nervous system disorders (neither hereditary nor degenerative)
Default principal diagnosis: inpatient No · outpatient No

Patient EducationClinical

Brain Diseases

Your brain is the control center of your body. It controls your thoughts, memory, speech, and movement. It regulates the function of many organs. It's part of your nervous system, which also includes your spinal cord and peripheral nerves. The nervous system sends signals between your brain and the rest of the body.

Read the full article at MedlinePlus

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

Convert G13.2 to ICD-9-CMHistory

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

ICD-9-CM
331.7 Cereb degen in oth dis
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 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About G13.2Overview

Is G13.2 a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report systemic atrophy primarily affecting the central nervous system in myxedema on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does G13.2 group to?

On inpatient claims, systemic atrophy primarily affecting the central nervous system in myxedema maps to MS-DRG 57, 56, with relative weights from 1.2835 to 2.2649 depending on complications. Higher weights mean higher Medicare reimbursement.

Can G13.2 be a principal diagnosis?

No. This is a manifestation code: systemic atrophy primarily affecting the central nervous system in myxedema describes the manifestation of an underlying disease rather than the disease itself, so the underlying condition is sequenced first.

What is coded first with G13.2?

The Code First note reads: underlying disease, such as: hypothyroidism (E03.-); myxedematous congenital iodine deficiency (E00.1). When one of these applies, it is sequenced before G13.2.

What is the ICD-9 equivalent of G13.2?

Under the General Equivalence Mappings, systemic atrophy primarily affecting the central nervous system in myxedema converts to ICD-9-CM 331.7 (cereb degen in oth dis). The mapping is approximate, so confirm the match fits the documentation.

Does G13.2 risk-adjust for Medicare Advantage payment?

Not for Medicare Advantage. G13.2 mapped to HCC 52 in the retired CMS-HCC V24 model, which last determined payment in 2025, but it maps to no category in the live V28 model; see all codes that no longer risk-adjust. It still risk-adjusts in the ESRD (V21) category 52 (Dementia Without Complication), ESRD (V24) category 52 (Dementia Without Complication), and RxHCC Part D (V08) category 112 (Dementia, Except Alzheimer's Disease).