Excludes1 pair
G10 vs G21-
G10 and G21 are not coded together. ICD-10-CM declares them mutually exclusive with an Excludes1 note — the two conditions are not expected to occur together, so exactly one of them is normally correct for a given encounter. The Official Guidelines carve out one exception: if the two conditions are clearly unrelated to each other, both may be reported.
The official note, declared on G21
Huntington's disease (G10)
G10
Huntington's disease
Billable
- Chapter 6
- Diseases of the nervous system
- Section
- G10-G14
Use when the record says
- Huntington's chorea
- Huntington's dementia
Indexed under
- Huntington's disease or chorea
- Chorea › hereditary
- Chorea › Huntington's
- Disease, diseased › Huntington's
- Huntington's disease or chorea › with dementia
Excludes1 is not always absolute: where two conditions covered by the note are genuinely unrelated, CMS guidance permits reporting both. Document the reasoning rather than assuming it. More on Excludes1 vs Excludes2 · FY2027