Alphabetic Index FY2027

G21

Secondary parkinsonism

FY2027Chapter 6: Diseases of the nervous system/G20–G26 Extrapyramidal and movement disorders

Non-billable headerNot valid on its own. Use one of the more specific codes under it.

G21 is a non-billable ICD-10-CM code category for secondary parkinsonism. Report a more specific code from it instead. It is part of the FY2027 code set, effective October 1, 2026. The more specific codes under it are G21.0 Malignant neuroleptic syndrome, G21.1 Other drug-induced secondary parkinsonism, G21.2 Secondary parkinsonism due to other external agents, G21.3 Postencephalitic parkinsonism and 3 more. Its coding notes include 4 Excludes1 entries and 8 Excludes2 entries.

Excludes1

Not coded here. The listed conditions generally should not be reported together.

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

Excludes2

Not included here. Both codes may be reported if the patient has both conditions.

Also from chapter/block level (8 notes)
Inherited from Chapter 6 Diseases of the nervous system
  • 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)

More specific codes under G21 7