Parkinson's Disease ICD-10-CM codes

G20 was expanded in FY2024. Parkinson's disease is now coded by dyskinesia and fluctuation status: G20.A1 (without dyskinesia, without mention of fluctuations), G20.A2 (without dyskinesia, with fluctuations), G20.B1 (with dyskinesia, without mention of fluctuations), and G20.B2 (with dyskinesia, with fluctuations). G20.C is parkinsonism, unspecified. When the record says only Parkinson's disease, assign G20.A1.

Fluctuations refers to documented motor fluctuations such as on-off phenomena or wearing-off. Dyskinesia means involuntary movements, usually levodopa induced. Do not assign the B or 2 codes without provider documentation of those terms.

Secondary parkinsonism is category G21: G21.11 neuroleptic-induced, G21.19 other drug-induced (add the T code for the drug), G21.4 vascular parkinsonism, G21.9 unspecified secondary parkinsonism. Malignant neuroleptic syndrome is G21.0. Parkinsonism caused by another named disease such as progressive supranuclear palsy is coded to that disease (G23.1).

Parkinson's disease dementia is coded G20.- first, then F02.- with severity and disturbance characters (F02.80 for unspecified severity without disturbance). Dementia with Lewy bodies is G31.83 followed by F02.-, and is a different diagnosis from Parkinson's disease with dementia.