G31.84 Mild cognitive impairment of uncertain or unknown etiology

The ICD-10-CM code for Mild cognitive impairment of uncertain or unknown etiology is G31.84 (FY2026). It is a billable, claim-ready diagnosis code.

Classification

Chapter

6: Diseases of the nervous system (G00-G99)

Section

G30-G32: Other degenerative diseases of the nervous system (G30-G32)

Category G31

17 codes (14 billable)

FY2026 Status

Stable since FY2024

Also Known As

ICD-10-CM Alphabetic Index entries that lead to G31.84:

• Impaired, impairment (function) › cognitive, mild, of uncertain or unknown etiology
• Disorder (of) › mild neurocognitive
• Impaired, impairment (function) › mild cognitive
• Disorder (of) › neurocognitive › mild (of uncertain or unknown etiology)
• Impaired, impairment (function) › mild cognitive › of uncertain or unknown etiology

Inclusion Terms

• Mild cognitive disorder NOS
• Mild neurocognitive disorder of uncertain or unknown etiology

U.S. Hospital Utilization

• An estimated 74,710 U.S. inpatient stays in 2023 included G31.84 among the documented diagnoses.
• 980 stays listed it as the principal diagnosis.

Source: National Inpatient Sample (NIS), Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality, 2016–2023. National survey-weighted estimates.

Official Coding Guidelines

Dominant/nondominant side (TOC entry)

a. Dominant/nondominant side ................................................................................................. 45

Pain - Category G89 (TOC entry)

b. Pain - Category G89.............................................................................................................. 45

Source: CMS — ICD-10-CM Official Guidelines for Coding and Reporting, FY2026

References

• CMS — ICD-10-CM Official Code Set and Guidelines, FY2026
• CDC/NCHS — ICD-10-CM Files and Browser Tool
• AHRQ — HCUP National Inpatient Sample, Frequencies by Diagnosis Code (2016–2023)