1. Home
  2. ICD-10-CM Codes
  3. G00–G99
  4. G20-G26
  5. G21
  6. 2024 ICD-10-CM Code G21
Version 2024
Non-Billable Code

2024 ICD-10-CM Diagnosis Code G21

Secondary parkinsonism

ICD-10-CM Code:
G21
ICD-10 Code for:
Secondary parkinsonism
Is Billable?
Not Valid for Submission
Code Navigator:

Code Classification

  • Diseases of the nervous system
    (G00–G99)
    • Extrapyramidal and movement disorders
      (G20-G26)
      • Secondary parkinsonism
        (G21)

G21 is a non-specific and non-billable diagnosis code code, consider using a code with a higher level of specificity for a diagnosis of secondary parkinsonism. The code is not specific and is NOT valid for the year 2024 for the submission of HIPAA-covered transactions. Category or Header define the heading of a category of codes that may be further subdivided by the use of 4th, 5th, 6th or 7th characters.

Specific Coding Applicable to Secondary parkinsonism

Non-specific codes like G21 require more digits to indicate the appropriate level of specificity. Consider using any of the following ICD-10-CM codes with a higher level of specificity when coding for secondary parkinsonism:

  • Use G21.0 for Malignant neuroleptic syndrome - BILLABLE CODE

  • G21.1 for Other drug-induced secondary parkinsonism - NON-BILLABLE CODE

  • Use G21.11 for Neuroleptic induced parkinsonism - BILLABLE CODE

  • Use G21.19 for Other drug induced secondary parkinsonism - BILLABLE CODE

  • Use G21.2 for Secondary parkinsonism due to other external agents - BILLABLE CODE

  • Use G21.3 for Postencephalitic parkinsonism - BILLABLE CODE

  • Use G21.4 for Vascular parkinsonism - BILLABLE CODE

  • Use G21.8 for Other secondary parkinsonism - BILLABLE CODE

  • Use G21.9 for Secondary parkinsonism, unspecified - BILLABLE CODE

Tabular List of Diseases and Injuries

The following annotation back-references are applicable to this diagnosis code. The Tabular List of Diseases and Injuries is a list of ICD-10-CM codes, organized "head to toe" into chapters and sections with coding notes and guidance for inclusions, exclusions, descriptions and more.


Type 1 Excludes

Type 1 Excludes
A type 1 excludes note is a pure excludes note. It means "NOT CODED HERE!" An Excludes1 note indicates that the code excluded should never be used at the same time as the code above the Excludes1 note. An Excludes1 is used when two conditions cannot occur together, such as a congenital form versus an acquired form of the same condition.
  • dementia with Parkinsonism G31.83
  • Huntington's disease G10
  • Shy-Drager syndrome G90.3
  • syphilitic Parkinsonism A52.19

Patient Education


Parkinson's Disease

Parkinson's disease (PD) is a type of movement disorder. It happens when nerve cells in the brain don't produce enough of a brain chemical called dopamine. Sometimes it is genetic, but most cases do not seem to run in families. Exposure to chemicals in the environment might play a role.

Symptoms begin gradually, often on one side of the body. Later they affect both sides. They include:

  • Trembling of hands, arms, legs, jaw and face
  • Stiffness of the arms, legs and trunk
  • Slowness of movement
  • Poor balance and coordination

As symptoms get worse, people with the disease may have trouble walking, talking, or doing simple tasks. They may also have problems such as depression, sleep problems, or trouble chewing, swallowing, or speaking.

There is no specific test for PD, so it can be difficult to diagnose. Doctors use a medical history and a neurological examination to diagnose it.

PD usually begins around age 60, but it can start earlier. It is more common in men than in women. There is no cure for PD. A variety of medicines sometimes help symptoms dramatically. Surgery and deep brain stimulation (DBS) can help severe cases. With DBS, electrodes are surgically implanted in the brain. They send electrical pulses to stimulate the parts of the brain that control movement.

NIH: National Institute of Neurological Disorders and Stroke


[Learn More in MedlinePlus]

Code History

  • FY 2024 - No Change, effective from 10/1/2023 through 9/30/2024
  • FY 2023 - No Change, effective from 10/1/2022 through 9/30/2023
  • FY 2022 - No Change, effective from 10/1/2021 through 9/30/2022
  • FY 2021 - No Change, effective from 10/1/2020 through 9/30/2021
  • FY 2020 - No Change, effective from 10/1/2019 through 9/30/2020
  • FY 2019 - No Change, effective from 10/1/2018 through 9/30/2019
  • FY 2018 - No Change, effective from 10/1/2017 through 9/30/2018
  • FY 2017 - No Change, effective from 10/1/2016 through 9/30/2017
  • FY 2016 - New Code, effective from 10/1/2015 through 9/30/2016. This was the first year ICD-10-CM was implemented into the HIPAA code set.