Skip to main content

G12.21 ICD-10-CM Code: Amyotrophic lateral sclerosis

Billing Status: YES. This is a valid, specific, and billable ICD-10-CM reference.

Coding at a Glance

Risk adjustment
CMS-HCC V28: 1 category · CMS-HCC V22 category 73 · RxHCC V08 category 154

Inpatient Payment Groups (MS-DRG)

Potential MS-DRG participation — not a DRG assignment.

MS-DRGs this diagnosis helps define, as principal or secondary, per the CMS ICD-10-CM/PCS MS-DRG Definitions Manual v43, Appendix B.

  • MS-DRG 056 — DEGENERATIVE NERVOUS SYSTEM DISORDERS WITH MCC (MDC 01)
  • MS-DRG 057 — DEGENERATIVE NERVOUS SYSTEM DISORDERS WITHOUT MCC (MDC 01)

A diagnosis appearing in a group's logic does not by itself determine the DRG assigned to a stay; the grouper uses the full claim.

Risk Adjustment (CMS-HCC)

Payment categories this diagnosis maps to under CMS-HCC V28, payment year 2026.

  • HCC 190 — Amyotrophic Lateral Sclerosis and Other Motor Neuron Disease, Spinal Muscular Atrophy

Other models: CMS-HCC V22 HCC 73 · RxHCC V08 HCC 154

Risk scores depend on the enrollee's full accepted diagnosis set and segment; a category mapping alone does not determine payment.

Code Overview

Amyotrophic lateral sclerosis is a billable ICD-10-CM diagnosis code (G12.21).

MedCoder summary Summary composed by MedCoder from this code's official ICD-10-CM record. The tabular instructional notes themselves appear verbatim below.

Indexed Clinical Terms (13)

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.

Verify Before Coding

  • Age-restricted: the Medicare Code Editor lists this as an adult (age 15-124) diagnosis; other ages are presumed incorrect.
  • 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 G12.21 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: M62.5 — Muscle wasting and atrophy, not elsewhere classified.

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

Referenced by 1 Code First instruction: F48.2 — Pseudobulbar affect.

Each of these codes carries a Code First note naming this condition — when that code is reported, THIS code is sequenced first, ahead of it.

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 111 clinically related codes on its CMS exclusion list.

Named in the grouper logic of 2 MS-DRGs: DRG 056 (MDC 01), DRG 057 (MDC 01).

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

Clinical classification (AHRQ CCSR):NVS006 — Other nervous system disorders (often hereditary or degenerative) (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.

E13.69 — Other specified diabetes mellitus with other specified complication, E13.8 — Other specified diabetes mellitus with unspecified complications, G11.3 — Cerebellar ataxia with defective DNA repair, G11.5 — Hypomyelination - hypogonadotropic hypogonadism - hypodontia, G11.6 — Leukodystrophy with vanishing white matter disease, G11.8 — Other hereditary ataxias, G11.9 — Hereditary ataxia, unspecified, G12.0 — Infantile spinal muscular atrophy, type I [Werdnig-Hoffman], G12.1 — Other inherited spinal muscular atrophy, G12.20 — Motor neuron disease, unspecified, G12.22 — Progressive bulbar palsy, G12.23 — Primary lateral sclerosis, G12.24 — Familial motor neuron disease, G12.25 — Progressive spinal muscle atrophy, G12.29 — Other motor neuron disease, G12.8 — Other spinal muscular atrophies and related syndromes, G12.9 — Spinal muscular atrophy, unspecified, G90.01 — Carotid sinus syncope, G90.09 — Other idiopathic peripheral autonomic neuropathy, G90.2 — Horner's syndrome, +90 more

Same CMS-HCC risk category (V28)

CMS maps these diagnoses to the same Hierarchical Condition Category (Amyotrophic Lateral Sclerosis and Other Motor Neuron Disease, Spinal Muscular Atrophy) for risk-adjusted payment.

G12.0 — Infantile spinal muscular atrophy, type I [Werdnig-Hoffman], G12.1 — Other inherited spinal muscular atrophy, G12.20 — Motor neuron disease, unspecified, G12.22 — Progressive bulbar palsy, G12.23 — Primary lateral sclerosis, G12.24 — Familial motor neuron disease, G12.25 — Progressive spinal muscle atrophy, G12.29 — Other motor neuron disease, G12.8 — Other spinal muscular atrophies and related syndromes, G12.9 — Spinal muscular atrophy, unspecified

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical category (Other nervous system disorders (often hereditary or degenerative)).

G11.2 — Late-onset cerebellar ataxia, G11.3 — Cerebellar ataxia with defective DNA repair, G11.4 — Hereditary spastic paraplegia, G11.5 — Hypomyelination - hypogonadotropic hypogonadism - hypodontia, G11.6 — Leukodystrophy with vanishing white matter disease, G11.8 — Other hereditary ataxias, G11.9 — Hereditary ataxia, unspecified, G12.0 — Infantile spinal muscular atrophy, type I [Werdnig-Hoffman], G12.1 — Other inherited spinal muscular atrophy, G12.20 — Motor neuron disease, unspecified, G12.22 — Progressive bulbar palsy, G12.23 — Primary lateral sclerosis, G12.24 — Familial motor neuron disease, G12.25 — Progressive spinal muscle atrophy, G12.29 — Other motor neuron disease, G12.8 — Other spinal muscular atrophies and related syndromes, G12.9 — Spinal muscular atrophy, unspecified, G21.0 — Malignant neuroleptic syndrome, G21.11 — Neuroleptic induced parkinsonism, G21.19 — Other drug induced secondary parkinsonism, +83 more

Same Index main term, other category

The ICD-10-CM Index to Diseases and Injuries files this code under the main terms “Atrophy, atrophic”, “Paralysis, paralytic”, “Sclerosis, sclerotic”; these codes share that main term but sit in a different category of the Tabular List.

E32.8 — Other diseases of thymus (thymus), E41 — Nutritional marasmus (infantile), E43 — Unspecified severe protein-calorie malnutrition (nutritional), E72.09 — Other disorders of amino-acid transport (renal, with, cystine storage disease), E75.23 — Krabbe disease (brain, Krabbe's), F44.4 — Conversion disorder with motor symptom or deficit (hysterical), F44.89 — Other dissociative and conversion disorders (accommodation, hysterical), G11.11 — Friedreich ataxia (Friedreich's), G11.4 — Hereditary spastic paraplegia (familial, spastic), G11.9 — Hereditary ataxia, unspecified (ataxic), G13.8 — Systemic atrophy primarily affecting central nervous system in other diseases classified elsewhere (systemic affecting central nervous system, in, specified disease NEC), G20.C — Parkinsonism, unspecified (agitans), G21.4 — Vascular parkinsonism (agitans, arteriosclerotic), G23.1 — Progressive supranuclear ophthalmoplegia [Steele-Richardson-Olszewski] (supranuclear), G23.8 — Other specified degenerative diseases of basal ganglia (Déjérine-Thomas), G25.9 — Extrapyramidal and movement disorder, unspecified (extrapyramidal), G31.01 — Pick's disease (brain, frontotemporal circumscribed), G31.09 — Other frontotemporal neurocognitive disorder (sclerosis, lobar), G31.1 — Senile degeneration of brain, not elsewhere classified (brain, senile NEC), G31.9 — Degenerative disease of nervous system, unspecified (brain), +253 more

Contextual Map

Every relationship of G12.21 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 G12.21 with these 2 related codes in Claim Check

Hierarchy

Referenced by Excludes1 notes

Referenced by Code First instructions

  • F48.2 — Pseudobulbar affect[Code First]: “amyotrophic lateral sclerosis (G12.21)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026

Clinical classification (CCSR)

Risk adjustment (CMS-HCC)

  • HCC 190 — Amyotrophic Lateral Sclerosis and Other Motor Neuron Disease, Spinal Muscular Atrophy [CMS-HCC]— CMS-HCC V28 · 2026

MS-DRG Grouper

MDC crossing

  • MDC 01 — Diseases and Disorders of the Nervous System[MDC crossing]: “Diseases and Disorders of the Nervous System — 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. 8,892 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2026

Index entries (13)

  • Amyotrophia, amyotrophy, amyotrophic, lateral sclerosis[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Atrophy, atrophic (of), Duchenne-Aran[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Atrophy, atrophic (of), muscle, muscular (diffuse) (general) (idiopathic) (primary), Duchenne-Aran[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Atrophy, atrophic (of), muscle, muscular (diffuse) (general) (idiopathic) (primary), progressive (bulbar)[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Atrophy, atrophic (of), muscle, muscular (diffuse) (general) (idiopathic) (primary), spinal, Aran-Duchenne[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Disease, diseased, motor neuron (bulbar) (mixed type) (spinal), amyotrophic lateral sclerosis[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Duchenne-Aran muscular atrophy[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Paralysis, paralytic (complete) (incomplete), amyotrophic[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • and 5 more

Nearest codes (12)

Change history

  • FY2016 — In the code set at ICD-10-CM adoption [Change history]— CMS release files (code change ledger) · icd10cm-fy2016

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
Risk adjustment Official source data
2026 Mid-Year Final ICD-10 Mappings + Model Software (cms.gov/files/zip/2026-midyear-final-icd-10-mappings.zip, 2026-midyear-final-model-software.zip) — CMS-HCC V28, PY2026 mid-year final release 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

Cite this page

Reference this page in a research guide, syllabus or article. The release is included because code content changes each year.

MedCoder.ai. "G12.21 — Amyotrophic lateral sclerosis." ICD-10-CM FY2026. https://medcoder.ai/icd10/code/g12.21-amyotrophic-lateral-sclerosis

Change history

  • FY2016 — October 1, 2015
    In the code set at ICD-10-CM adoption
    Amyotrophic lateral sclerosis

No changes since FY2016 — additions, deletions, description changes and billable-status changes are tracked through FY2027 (effective October 1, 2026), and none are recorded for this code. Note changes are tracked from FY2027 only.

Nearest Codes in This Family

Official ICD-10-CM classifications closest to G12.21 in its code family, with their registry titles.

View all codes in the G12 family