ICD-10 G31.1
Billable / Specific HCC v28: 52Senile degeneration of brain, not elsewhere classified
About ICD-10-CM G31.1
ICD-10-CM code G31.1 represents Senile degeneration of brain, not elsewhere classified. This is a billable/specific code in the Nervous System chapter (block G31). The 2026 edition of ICD-10-CM G31.1 became effective on October 1, 2025.
Coding Tips for G31.1
Specialist guidance from the PayerReady Medical Coding Team. Specificity warnings, HCC capture rules, sequencing notes.
G31.1 is a CMS-HCC v28 risk-adjustment code (category 52). To count for the patient Risk Adjustment Factor (RAF), document the diagnosis with MEAT language each calendar year: Monitored, Evaluated, Assessed, Treated. A diagnosis on the problem list alone does not satisfy CMS RADV audit standards. Include the diagnosis in the assessment with current status and current treatment plan.
Type 1 Excludes
Pure excludes, these codes can never be coded together with G31.1. The conditions are mutually exclusive (e.g., congenital vs acquired forms).
- Alzheimer's disease (G30.-)
- senility NOS (R41.81)
Medicare Advantage HCC Impact
Capture this diagnosis annually for accurate risk adjustment. Missed HCC captures are the #1 revenue leak in Medicare Advantage risk programs.
Medicare LCD Coverage for G31.1
Local Coverage Determinations (LCDs) from CMS MACs that list G31.1 as a covered diagnosis.
Showing top 10 of 158 total . Click a CPT for full coverage scope.
Commercial Payer Coverage
Coverage policies from major commercial payers referencing G31.1.
2 Cigna
5 Medicare
CPT Codes Commonly Billed with G31.1
Procedures frequently paired with this diagnosis based on PayerReady's Dx↔Px linkage data.
- G0252 CMS LCD: Billing and Coding: NCD Coding Article for Positron Emission Tomography (PET) Scans Used for Non-Oncologic Conditions CMS LCD
- 78608 CMS LCD: Billing and Coding: NCD Coding Article for Positron Emission Tomography (PET) Scans Used for Non-Oncologic Conditions CMS LCD
- A9597 CMS LCD: Billing and Coding: NCD Coding Article for Positron Emission Tomography (PET) Scans Used for Non-Oncologic Conditions CMS LCD
- A9601 CMS LCD: Billing and Coding: NCD Coding Article for Positron Emission Tomography (PET) Scans Used for Non-Oncologic Conditions CMS LCD
- G0235 CMS LCD: Billing and Coding: NCD Coding Article for Positron Emission Tomography (PET) Scans Used for Non-Oncologic Conditions CMS LCD
- 78609 CMS LCD: Billing and Coding: NCD Coding Article for Positron Emission Tomography (PET) Scans Used for Non-Oncologic Conditions CMS LCD
- A9552 CMS LCD: Billing and Coding: NCD Coding Article for Positron Emission Tomography (PET) Scans Used for Non-Oncologic Conditions CMS LCD
- G0219 CMS LCD: Billing and Coding: NCD Coding Article for Positron Emission Tomography (PET) Scans Used for Non-Oncologic Conditions CMS LCD
- A9598 CMS LCD: Billing and Coding: NCD Coding Article for Positron Emission Tomography (PET) Scans Used for Non-Oncologic Conditions CMS LCD
- G0539 CMS LCD: Billing and Coding: Home Health Skilled Nursing Care-Teaching and Training: Alzheimer's Disease and Behavioral Disturbances CMS LCD
Convert G31.1 to ICD-9-CM
Per CMS General Equivalence Mappings (GEMs), useful for legacy data review and historical claim analysis.
| ICD-10 | ICD-9 | Mapping Flags |
|---|---|---|
| G31.1 | 3312 | 00000 |
Flags format (5 digits): Approximate · No Map · Combination · Scenario · Choice List. Source: CMS 2017 GEMs (final version).
Codes Adjacent To G31.1
Other codes in section G30-G32 (Other degenerative diseases of the nervous system).
ICD-10 G31.1, Billing FAQ
Is ICD-10 code G31.1 billable? +
Yes, G31.1 is a billable ICD-10-CM code that can appear as a primary or secondary diagnosis on claims.
What codes are Type 1 Excludes for G31.1? +
Type 1 Excludes (never code together with G31.1): Alzheimer's disease (G30.-); senility NOS (R41.81)
Does G31.1 affect Medicare Advantage HCC risk adjustment? +
Yes. G31.1 maps to CMS-HCC v28 category 52. Capture this diagnosis annually for accurate Medicare Advantage risk score.
What CPT codes are commonly billed with G31.1? +
Procedures frequently paired with G31.1 include: G0252, 78608, A9597, A9601, G0235.
What ICD-9 codes does G31.1 map to? +
Per CMS GEMs, G31.1 maps to ICD-9 codes: 3312. Useful for legacy data review and historical claim analysis.
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Reviewed by the PayerReady Medical Coding Team
Verified against the CMS 2026 code set on July 16, 2026.
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