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ICD-10 Guide
ICD-10 CodesChapter 6: Diseases of the nervous systemG21

G21

Billable

Secondary parkinsonism

Chapter 6:Diseases of the nervous system

BILLABLE STATUSYes
IMPLEMENTATION DATEOctober 1, 2015
LAST UPDATED09/05/2025

Code Description

ICD-10 G21 is a billable code used to indicate a diagnosis of secondary parkinsonism.

Key Diagnostic Point:

Secondary parkinsonism refers to a group of movement disorders that exhibit symptoms similar to Parkinson's disease but are caused by other underlying conditions or factors. Unlike primary Parkinson's disease, which is idiopathic, secondary parkinsonism can result from various etiologies including neurodegenerative diseases, vascular issues, infections, metabolic disorders, and exposure to certain medications, particularly dopaminergic agents. Symptoms typically include bradykinesia, rigidity, and tremors, which can significantly impact a patient's quality of life. The diagnosis of secondary parkinsonism requires a thorough clinical evaluation, including a detailed patient history, neurological examination, and sometimes imaging studies to identify the underlying cause. Treatment strategies often focus on managing the symptoms and addressing the root cause, which may involve adjusting or discontinuing medications, physical therapy, or other interventions. Understanding the nuances of secondary parkinsonism is crucial for accurate coding and appropriate patient management.

Code Complexity Analysis

Complexity Rating: Medium

Medium Complexity

Complexity Factors

  • Variety of underlying causes leading to secondary parkinsonism.
  • Differentiation from primary Parkinson's disease.
  • Potential for overlapping symptoms with other movement disorders.
  • Need for comprehensive documentation of the underlying condition.

Audit Risk Factors

  • Inadequate documentation of the underlying cause.
  • Misclassification of primary vs. secondary parkinsonism.
  • Failure to document medication history, especially dopaminergic agents.
  • Lack of comprehensive neurological examination findings.

Specialty Focus

Medical Specialties

Neurology

Documentation Requirements

Detailed neurological examination findings, history of symptoms, and any relevant imaging or lab results.

Common Clinical Scenarios

Patients presenting with tremors, rigidity, and bradykinesia after starting new medications or with a history of stroke.

Billing Considerations

Ensure clear documentation of the timeline of symptom onset in relation to medication use or other potential causes.

Geriatrics

Documentation Requirements

Comprehensive assessment of functional status, medication review, and evaluation of comorbid conditions.

Common Clinical Scenarios

Older adults presenting with movement disorders after polypharmacy or with multiple chronic conditions.

Billing Considerations

Focus on the impact of secondary parkinsonism on daily living activities and overall health.

Coding Guidelines

Inclusion Criteria

Use G21 When
  • According to ICD
  • 10 guidelines, G21 should be used when parkinsonism is secondary to another condition
  • Coders must ensure that the underlying cause is documented and coded appropriately, as this is critical for accurate billing and treatment planning

Exclusion Criteria

Do NOT use G21 When
No specific exclusions found.

Related CPT Codes

99214CPT Code

Established patient office visit, level 4

Clinical Scenario

Used for follow-up visits for patients with secondary parkinsonism.

Documentation Requirements

Document the patient's history, examination findings, and treatment plan.

Specialty Considerations

Neurologists should focus on detailed neurological assessments.

ICD-10 Impact

Diagnostic & Documentation Impact

Enhanced Specificity

ICD-10 Improvements

The transition to ICD-10 has allowed for more specific coding of secondary parkinsonism, enabling better tracking of the condition and its causes, which can improve patient care and treatment outcomes.

ICD-9 vs ICD-10

The transition to ICD-10 has allowed for more specific coding of secondary parkinsonism, enabling better tracking of the condition and its causes, which can improve patient care and treatment outcomes.

Reimbursement & Billing Impact

The transition to ICD-10 has allowed for more specific coding of secondary parkinsonism, enabling better tracking of the condition and its causes, which can improve patient care and treatment outcomes.

Resources

Clinical References

  • •
    ICD-10-CM Official Guidelines for Coding and Reporting

Coding & Billing References

  • •
    ICD-10-CM Official Guidelines for Coding and Reporting

Frequently Asked Questions

What is the difference between primary and secondary parkinsonism?

Primary parkinsonism, or Parkinson's disease, is idiopathic and has no identifiable cause, while secondary parkinsonism is caused by other medical conditions or factors, such as medications or metabolic disorders.