ICD-10 G37.9
Billable / Specific HCC v28: 77 CCDemyelinating disease of central nervous system, unspecified
About ICD-10-CM G37.9
ICD-10-CM code G37.9 represents Demyelinating disease of central nervous system, unspecified. This is a billable/specific code in the Nervous System chapter (block G37). The 2026 edition of ICD-10-CM G37.9 became effective on October 1, 2025.
Coding Tips for G37.9
Specialist guidance from the PayerReady Medical Coding Team. Specificity warnings, HCC capture rules, sequencing notes.
G37.9 is a CMS-HCC v28 risk-adjustment code (category 77). 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.
G37.9 is designated CC for MS-DRG grouping. On inpatient claims, this code can shift the DRG to the with-CC variant when documented as a present-on-admission secondary diagnosis. Hospital CDI programs flag CC opportunities during chart review. Failure to capture this code may leave 30 to 80 percent of the inpatient stay revenue unrealized.
Inclusion Terms / Approximate Synonyms
Clinical terms and conditions classified under G37.9. Per CMS ICD-10-CM Tabular 2026.
- Clinically isolated syndromes
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.
Inpatient DRG Impact, CC
codes Demyelinating disease of central nervous system, unspecified. As a Complication/Comorbidity (CC), this contributes to DRG severity adjustment when documented alongside the principal diagnosis.
Medicare LCD Coverage for G37.9
Local Coverage Determinations (LCDs) from CMS MACs that list G37.9 as a covered diagnosis.
Showing top 10 of 279 total . Click a CPT for full coverage scope.
Commercial Payer Coverage
Coverage policies from major commercial payers referencing G37.9.
2 Cigna
5 Medicare
2 Aetna
1 NY Medicaid
CPT Codes Commonly Billed with G37.9
Procedures frequently paired with this diagnosis based on PayerReady's Dx↔Px linkage data.
Convert G37.9 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 |
|---|---|---|
| G37.9 | 3419 | 10000 |
Flags format (5 digits): Approximate · No Map · Combination · Scenario · Choice List. Source: CMS 2017 GEMs (final version).
Codes Adjacent To G37.9
Other codes in section G35-G37 (Demyelinating diseases of the central nervous system).
ICD-10 G37.9, Billing FAQ
Is ICD-10 code G37.9 billable? +
Yes, G37.9 is a billable ICD-10-CM code that can appear as a primary or secondary diagnosis on claims.
What other names or terms map to G37.9? +
ICD-10 G37.9 includes: Clinically isolated syndromes.
Does G37.9 affect Medicare Advantage HCC risk adjustment? +
Yes. G37.9 maps to CMS-HCC v28 category 77. Capture this diagnosis annually for accurate Medicare Advantage risk score.
Is G37.9 a CC or MCC for inpatient DRG? +
Yes, this code is designated as CC. Documenting as a secondary diagnosis on inpatient claims can shift the DRG to a higher-weighted category.
What CPT codes are commonly billed with G37.9? +
Procedures frequently paired with G37.9 include: G0161, G0153.
What ICD-9 codes does G37.9 map to? +
Per CMS GEMs, G37.9 maps to ICD-9 codes: 3419. 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 May 31, 2026.
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