DxCodebookFY2027 · Oct 1, 2026 – Sep 30, 2027

Category · FY2027

G21 Secondary parkinsonism

  • Header · not billable

G21 is not billable. The category heads 8 billable codes in FY2027, grouped under 7 subdivisions.

Index → code

  • Parkinsonism (idiopathic) (primary)vascular → G21.4
  • Parkinsonism (idiopathic) (primary)secondary → G21.9
  • Parkinsonism (idiopathic) (primary)arteriosclerotic → G21.4

Where it sits

  1. Chapter 6 Diseases of the nervous system (G00-G99)
  2. G20-G26 Extrapyramidal and movement disorders (G20-G26)
  3. G21 Secondary parkinsonism
Billable codes
8
Subdivisions
7
CC / MCC codes
6 / 1
HCC V28 codes
4
New FY2027
0
Index entries
17

Codes in G21

  1. G21.0
    Malignant neuroleptic syndrome
    BillableMCC
    Excludes1 1, Use additional code 1

    Excludes1

    • neuroleptic induced parkinsonism (G21.11) G21.11

    Use additional code

  2. G21.1
    Other drug-induced secondary parkinsonism
    Header
  3. G21.11
    Neuroleptic induced parkinsonism
    BillableCC
    Excludes1 1, Use additional code 1

    Excludes1

    • malignant neuroleptic syndrome (G21.0) G21.0

    Use additional code

  4. G21.19
    Other drug induced secondary parkinsonism
    BillableCC
    Inclusion terms 1, Use additional code 1

    Inclusion terms

    • Other medication-induced parkinsonism

    Use additional code

    • code for adverse effect, if applicable, to identify drug (T36-T50 with fifth or sixth character 5) T36 T50
  5. G21.2
    Secondary parkinsonism due to other external agents
    BillableCC
    Code first 1

    Code first

    • (T51-T65) to identify external agent T51 T65
  6. G21.3
    Postencephalitic parkinsonism
    BillableCC199
  7. G21.4
    Vascular parkinsonism
    Billable199
  8. G21.8
    Other secondary parkinsonism
    BillableCC199
  9. G21.9
    Secondary parkinsonism, unspecified
    BillableCC199

CC/MCC: as a secondary diagnosis, unless the principal diagnosis is on the code’s PDX exclusion list (MS-DRG v44 Appendix C; list on the code card).

Sources of each column.

Instructions

At G21

Excludes1

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

Notes that also apply

Chapter 6 instructions (Excludes2 8): printed on the chapter 6 page.

Index entries

  • Parkinsonism (idiopathic) (primary)neuroleptic induced → G21.11
  • Parkinsonism (idiopathic) (primary)medication-induced NEC → G21.19
  • Parkinsonism (idiopathic) (primary)treatment-induced NEC → G21.19
  • Parkinsonism (idiopathic) (primary)postencephalitic → G21.3
  • Parkinsonism (idiopathic) (primary)arteriosclerotic → G21.4
  • Parkinsonism (idiopathic) (primary)vascular → G21.4
  • Parkinsonism (idiopathic) (primary)secondary → G21.9
  • Syndromemalignantneuroleptic → G21.0
  • Parkinsonism (idiopathic) (primary)due todrugs NEC → G21.19
  • Paralysis, paralytic (complete) (incomplete)agitansarteriosclerotic → G21.4
  • Parkinsonism (idiopathic) (primary)secondaryspecified NEC → G21.8
  • Parkinsonism (idiopathic) (primary)due todrugs NECneuroleptic → G21.11
  • Parkinsonism (idiopathic) (primary)secondarydue todrugs NEC → G21.19
  • Parkinsonism (idiopathic) (primary)secondarydue toexternal agents NEC → G21.2
  • Parkinsonism (idiopathic) (primary)secondarydue toencephalitis → G21.3
  • Parkinsonism (idiopathic) (primary)secondarydue toarteriosclerosis → G21.4
  • Parkinsonism (idiopathic) (primary)secondarydue todrugs NECneuroleptic → G21.11

NCHS Alphabetic Index. Index first, then the Tabular List.

Hierarchy