G31.84 — Mild cognitive impairment of uncertain or unknown etiology
G31.84 is a billable, specific ICD-10-CM code for mild cognitive impairment of uncertain or unknown etiology. It is valid for submission on a claim.
Excludes1 — never code together
These conditions cannot occur together. Billing both on the same encounter is a denial.
- age related cognitive decline (R41.81)
- altered mental status (R41.82)
- cerebral degeneration (G31.9)
- cerebrovascular diseases (I60-I69)
- change in mental status (R41.82)
- cognitive deficits following (sequelae of) cerebral hemorrhage or infarction (I69.01-, I69.11-, I69.21-, I69.31-, I69.81-, I69.91-)
- cognitive impairment due to intracranial or head injury (S06.-)
- dementia (F01.-, F02.-, F03.-)
- mild neurocognitive disorder due to a known physiological condition (F06.7-)
- neurologic neglect syndrome (R41.4)
- personality change, nonpsychotic (F68.8)
Use additional code
Add a secondary code to capture the detail described below.
Inclusion terms
Alternative wordings a physician may use in the chart for this same code.
- Mild cognitive disorder NOS
- Mild neurocognitive disorder of uncertain or unknown etiology
Other codes that can never be billed with G31.84
These codes carry an Excludes1 note pointing at G31.84. The conflict binds both ways, but ICD-10-CM only writes it down on one side — so you would not find this by reading G31.84 alone.
Risk adjustment
G31.84 does not map to an HCC and does not risk-adjust under CMS-HCC V28. That is normal — most ICD-10 codes do not. It still needs to be coded correctly; it just will not move a RAF score.
Medicare coverage
G31.84 is named in 8 Medicare coverage policies — 6 listing it as supporting medical necessity, and 2 listing it as NOT covered. Which of them applies to you depends on your Medicare contractor, and coverage genuinely differs by state.
- A52434Health and Behavior Assessment/Intervention – Medical Policy Articlenot covered
- A56562Billing and Coding: Health and Behavior Assessment/Interventionnot covered
- A54111Billing and Coding: Speech Language Pathology (SLP) Services: Communication Disorders
- A56937Billing and Coding: Psychiatry and Psychology Services
How G31.84 is indexed
Coders do not find codes by browsing the tabular list — they look them up in the alphabetic index, under the word the physician wrote. These are the index entries that lead here, so you can see which chart wordings map to G31.84.
- Disorder›mild neurocognitive
- Impaired, impairment›cognitive, mild, of uncertain or unknown etiology
- Impaired, impairment›mild cognitive
- Disorder›neurocognitive›mild(of uncertain or unknown etiology)
- Impaired, impairment›mild cognitive›of uncertain or unknown etiology
Related codes at this level
Codes that share G31.8. If G31.84 is not quite right, the correct code is usually one of these.
Questions about G31.84
- Is G31.84 a billable ICD-10-CM code?
- Yes. G31.84 is a billable, specific ICD-10-CM code and is valid for submission on a claim.
- Where does G31.84 sit in the tabular list?
- Diseases of the nervous system (G00-G99), in the block Other degenerative diseases of the nervous system (G30-G32).
- What cannot be coded together with G31.84?
- G31.84 carries an Excludes1 note, which means the conditions it lists can never be coded together with it on the same encounter.