U.S. ICD-10-CM · FY 2027

G21 ICD-10-CM Code: Secondary parkinsonism

A clear reference for the official code description, hierarchy, and related coding information from the FY 2027 U.S. release.

Code definition

Official description

G21

Secondary parkinsonism

ICD-10-CM diagnosis code · United States clinical modification

Classification

Where G21 sits

  1. 1

    Chapter 6

    Diseases of the nervous system (G00-G99)

  2. 2

    Section

    Extrapyramidal and movement disorders (G20-G26)

  3. 3

    Category G21

    Secondary parkinsonism

  4. 4

    Code G21

    Secondary parkinsonism

More specific choices

Codes under G21

G21 is a non-billable category. Choose the child code that best matches the documented diagnosis.

Documentation details

Notes for this code

Inclusion terms

No inclusion terms are listed for G21.

Code first

No “code first” instruction is listed for G21.

Use additional code

No “use additional code” instruction is listed for G21.

Excludes1

Conditions that should not be reported together with this code.

  • Huntington's disease (G10)
  • neurocognitive disorder with Lewy bodies (G31.83)
  • Shy-Drager syndrome (G90.3)
  • syphilitic Parkinsonism (A52.19)

Excludes2

Conditions not included here that may be reported separately when present.

No Excludes2 note is listed for G21.

Transparency

Source and release

Data release

U.S. ICD-10-CM · FY 2027

Effective date

Oct 1, 2026

This reference is generated from Vero’s ICD-10-CM description, hierarchy, and code-note dataset. The visible content and structured data share that source.

Review the CDC/NCHS ICD-10-CM source

Code-specific guidance

Frequently asked questions

What does ICD-10-CM code G21 mean?

G21 is the FY 2027 U.S. ICD-10-CM code for “Secondary parkinsonism.”

Is G21 a billable or specific ICD-10-CM code?

No. G21 has more specific child codes in the FY 2027 reference data. Select the code that matches the documentation and confirm the active code set and payer requirements.

Where is G21 located in ICD-10-CM?

G21 is listed in Chapter 6, Diseases of the nervous system (G00-G99), within Extrapyramidal and movement disorders (G20-G26) (G20–G26), under category G21, Secondary parkinsonism.

What coding notes are listed for G21?

No inclusion terms are listed for G21 in this reference record. No code-first instruction is listed. Excludes1 notes: Huntington's disease (G10); neurocognitive disorder with Lewy bodies (G31.83); Shy-Drager syndrome (G90.3); syphilitic Parkinsonism (A52.19). No Excludes2 note is listed.

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