ICD-10-CM G21 is the diagnosis code for Secondary parkinsonism. This code falls under the section "Extrapyramidal and movement disorders" within Chapter 6 — Diseases of the nervous system (G00-G99). It is a non-billable/non-specific ICD-10-CM code that should not be used for reimbursement. A more specific sub-code is required for billing. Medical coders and healthcare providers use this code to document and classify diagnoses in electronic health records, insurance claims, and clinical databases.
The following conditions should never be coded at the same time as G21. They are mutually exclusive:
Understanding where G21 sits in the ICD-10-CM classification helps ensure proper coding:
No, G21 is a non-billable/non-specific code. You should use a more specific sub-code for billing and reimbursement.
G21 is the ICD-10-CM diagnosis code for "Secondary parkinsonism". It is used by healthcare providers to classify and document this condition in medical records and insurance claims.
G21 is located in Section G20-G26 — "Extrapyramidal and movement disorders" within Chapter 6 of the ICD-10-CM Tabular List.
G21 has 7 sub-code(s) that provide more specific detail: G21.0, G21.1, G21.2, G21.3, G21.4 and more.
Use G21 when the patients documented diagnosis matches "Secondary parkinsonism" and the clinical documentation supports this level of specificity. Always verify with the latest ICD-10-CM guidelines and payer requirements.
The ICD-10-CM code for Secondary parkinsonism is G21.
No, G21 is non-billable. Use a more specific sub-code for primary diagnosis billing.
G21 is in Chapter 6 of the ICD-10-CM Tabular List.
Type 1 Excludes for G21 include: Huntington's disease (G10); neurocognitive disorder with Lewy bodies (G31.83); Shy-Drager syndrome (G90.3) and more.
Yes, G21 is a valid ICD-10-CM code for the 2026 fiscal year, subject to official CMS updates.