The ICD-10-CM code for Parkinson's disease is
G20
when documented without further specification.
Parkinson's disease is category G20, built from two documented axes — dyskinesia (G20.A without, G20.B with) and motor fluctuations (…1 without, …2 with) — plus G20.C for unspecified parkinsonism. Assign the leaf code that matches the documentation.
Symptom code vs. confirmed diagnosis
G20 is a specific diagnosis, not a symptom code. Isolated tremor or bradykinesia without a Parkinson's diagnosis is coded to the symptom. Once the record documents Parkinson's disease, assign the specific G20 leaf code for the documented dyskinesia and fluctuation status.
Which Code Should You Use?
G20
⚠ Non-Billable
— Parkinson's disease
Parkinson's disease — category header; assign a specific G20 leaf code per documentation.
G20.A1
✓ Billable
— Parkinson's disease without dyskinesia, without mention of fluctuations
Parkinson's disease without dyskinesia, without mention of fluctuations.
G20.A2
✓ Billable
— Parkinson's disease without dyskinesia, with fluctuations
Parkinson's disease without dyskinesia, with fluctuations.
G20.B1
✓ Billable
— Parkinson's disease with dyskinesia, without mention of fluctuations
Parkinson's disease with dyskinesia, without mention of fluctuations.
G20.B2
✓ Billable
— Parkinson's disease with dyskinesia, with fluctuations
Parkinson's disease with dyskinesia, with fluctuations.
What to Document
- Presence or absence of dyskinesia (G20.A vs G20.B).
- Presence or absence of motor (on-off) fluctuations (drives the further character).
- Parkinson's disease vs unspecified parkinsonism (G20.C).
- Any associated dementia or mild neurocognitive disorder — G20 carries a use-additional-code note to identify it (F02.8-, F06.7-).
Common Documentation Pitfalls
- G20 is a category header — assign a specific G20 leaf code (…A1/A2/B1/B2 or G20.C), not bare G20.
- Match both axes — don't default to a "without fluctuations" code when on-off motor fluctuations are documented.
Instructional Notes for G20
Use Additional Code
- code, if applicable, to identify:
- dementia with anxiety (F02.84, F02.A4, F02.B4, F02.C4)
- dementia with behavioral disturbance (F02.81-, F02.A1-, F02.B1-, F02.C1-)
- dementia with mood disturbance (F02.83, F02.A3, F02.B3, F02.C3)
- dementia with psychotic disturbance (F02.82, F02.A2, F02.B2, F02.C2)
- dementia without behavioral disturbance (F02.80, F02.A0, F02.B0, F02.C0)
- mild neurocognitive disorder due to known physiological condition (F06.7-)
Coding Notes
G20 became a category — code the two documented axes, dyskinesia (A/B) and motor fluctuations (…1/…2), or G20.C for unspecified parkinsonism. G20 also carries a use-additional-code note to identify any associated dementia (F02.8-) or mild neurocognitive disorder (F06.7-).