What is ICD-10 code G47.419?

G47.419 is the ICD-10-CM diagnosis code for Narcolepsy without cataplexy. A sleep disorder characterized by excessive daytime sleepiness and sudden sleep attacks without episodes of muscle weakness or paralysis. It belongs to the ICD-10-CM chapter for diseases of the nervous system (g00-g99). G47.419 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. G47.419 is part of the FY2026 ICD-10-CM code set published by the CMS National Center for Health Statistics and used on Medicare, Medicaid, and commercial claims in the United States.

Yes. G47.419 is a billable ICD-10-CM code that can be reported on professional and institutional claims as a primary or secondary diagnosis when the provider documentation supports the specific condition described. Billable codes in ICD-10-CM are coded to the highest level of specificity available for the documented diagnosis. G47.419 is current for fiscal year 2026 and remains in the active CMS ICD-10-CM code set published by the National Center for Health Statistics.

What is the V28 vs V24 difference for G47.419?

G47.419 does not map to a payment HCC under either the CMS-HCC V28 risk adjustment model or the older V24 model. V28 reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition. Because neither model rewards G47.419 with a risk adjustment factor, it contributes zero to a Medicare Advantage beneficiary's RAF score in either version. Coders should check whether provider documentation supports a more specific child code that does map to a payment HCC.

What should coders know when reporting G47.419?

This code is used when cataplexy is explicitly absent or not documented Narcolepsy type 2 does not include cataplexy; verify documentation confirms absence of muscle weakness episodes

G47.419: Narcolepsy without cataplexy — ICD-10

ICD-10-CM Code View

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Code lookupG47.419Effective periodFY2026 Apr Update (Apr 1-Sep 30)

FY 2026 Apr update / Diseases of the nervous system (G00-G99) / Episodic and paroxysmal disorders (G40-G47)

G47.419

Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidance

Narcolepsy without cataplexy

A sleep disorder characterized by excessive daytime sleepiness and sudden sleep attacks without episodes of muscle weakness or paralysis.

Buddy Insight

Narcolepsy without cataplexy (Type 2 narcolepsy) is characterized by excessive daytime sleepiness with abnormal sleep architecture but without the muscle tone loss seen in cataplexy.

CMS-HCC V28

Not risk-adjusted for this model/period.

RAF 0

CMS-HCC V24

Not risk-adjusted for this model/period.

RAF 0

ACA/HHS

Not risk-adjusted for this model/period.

RAF 0

ESRD/PACE

Not risk-adjusted for this model/period.

RAF 0

RXHCC

Mapped

HCC 355

Narcolepsy

RAF 0.0

Code Trumping

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Code Book Path

Official

G47.4Narcolepsy and cataplexy

G47.41Narcolepsy

G47.419Narcolepsy without cataplexy

Inclusion Terms

Official

Narcolepsy NOS

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for G47.419 in this effective period.

Related Child Codes

Official

G47.411Narcolepsy with cataplexy

Includes

Official

ICD-10-CM does not list Includes notes for G47.419 in this effective period.

Excludes 1

Official

ICD-10-CM does not list Excludes 1 notes for G47.419 in this effective period.

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for G47.419 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for G47.419 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for G47.419 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Diagnosis of narcolepsy with documented excessive daytime sleepiness

Documentation of absent cataplexy (distinguishes Type 2 from Type 1)

MSLT results showing mean sleep latency <=8 minutes with >=2 sleep-onset REM periods

Normal cerebrospinal fluid hypocretin-1 levels (if tested) — helps confirm Type 2

MEAT Support

HCC Buddy guidance

Diagnosis of narcolepsy with documented excessive daytime sleepiness

Documentation of absent cataplexy (distinguishes Type 2 from Type 1)

MSLT results showing mean sleep latency <=8 minutes with >=2 sleep-onset REM periods

Normal cerebrospinal fluid hypocretin-1 levels (if tested) — helps confirm Type 2

Audit Caution

HCC Buddy guidance

Not documenting the absence of cataplexy — distinguishes Type 2 from Type 1 narcolepsy

Coding as primary when a secondary cause exists

Using hypersomnia codes (G47.1x) when full narcolepsy diagnostic criteria are met

Not obtaining or documenting MSLT results to confirm narcolepsy vs. other hypersomnia

Common Mistakes

HCC Buddy guidance

G47.411 (Narcolepsy with cataplexy) — Type 1 narcolepsy; includes cataplexy episodes

G47.10 (Hypersomnia, unspecified) — nonspecific; narcolepsy has specific diagnostic criteria

G47.429 (Narcolepsy in conditions classified elsewhere, without cataplexy) — use for secondary narcolepsy

G47.11-G47.19 (Idiopathic hypersomnia) — excessive sleep without narcolepsy sleep architecture on MSLT

Last updated: FY2026 ICD-10-CM Apr update, Apr 1, 2026 through Sep 30, 2026. CMS-HCC V28 is 100% phased in for payment year 2026.

Is G47.419 an HCC code?

No. G47.419 is a billable ICD-10-CM code but does not map to any HCC category in V28, V24, ESRD, or RxHCC.

HCC Category Mapping

RxHCCHCC 355, Narcolepsy

0.000

RAF weights shown are the community, non-dual, aged base weights from the CMS risk adjustment model file. Actual per-patient RAF contribution depends on member segment, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains in use during the transition and for historical data.

Work G47.419 in the Code Book — tabular path, V28 RAF, and MEAT checklist →

MEAT Criteria for G47.419

For G47.419to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically, it has to be re-documented and supported each calendar year.

MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
EEvaluate: test results, medication response, or physical findings reviewed by the provider
AAssess: explicit mention in the assessment or plan with acknowledgment of status
TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis

Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed G47.419 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

G47.419 is the ICD-10-CM diagnosis code for narcolepsy without cataplexy. A sleep disorder characterized by excessive daytime sleepiness and sudden sleep attacks without episodes of muscle weakness or paralysis. G47.419 sits in the ICD-10-CM chapter for diseases of the nervous system (g00-g99), within the section covering episodic and paroxysmal disorders (g40-g47).

G47.419 is a billable ICD-10-CM code but does not map to a payment HCC under the CMS-HCC V28, V24, ESRD, or RxHCC risk adjustment models. It can be reported on Medicare Advantage encounter data submissions but it does not contribute to a beneficiary's RAF score and therefore does not affect risk-adjusted payments to the plan.

Maps to RxHCC 355 (Narcolepsy and Cataplexy) with a RAF weight of 0.000 in the prescription drug model. No mapping to CMS-HCC V28 or V24 payment models, so this code does not directly affect Medicare Advantage capitation payments. The RxHCC mapping reflects pharmacy costs for wake-promoting agents (modafinil, armodafinil, solriamfetol, pitolisant) and sodium oxybate for cataplexy. No hierarchies apply within payment models.

HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for G47.419 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•This code is used when cataplexy is explicitly absent or not documented
•Narcolepsy type 2 does not include cataplexy; verify documentation confirms absence of muscle weakness episodes

Clinical Significance

Narcolepsy without cataplexy (Type 2 narcolepsy) is characterized by excessive daytime sleepiness with abnormal sleep architecture but without the muscle tone loss seen in cataplexy. While less severe than Type 1, it still significantly impacts daily functioning, employment, and driving safety. The absence of cataplexy means normal or borderline hypocretin levels, and the condition may evolve into Type 1 over time.

Documentation Requirements

✓Diagnosis of narcolepsy with documented excessive daytime sleepiness
✓Documentation of absent cataplexy (distinguishes Type 2 from Type 1)
✓MSLT results showing mean sleep latency <=8 minutes with >=2 sleep-onset REM periods
✓Normal cerebrospinal fluid hypocretin-1 levels (if tested) — helps confirm Type 2
✓Impact on daily functioning documented
✓Current treatment plan (typically stimulants/wake-promoting agents without cataplexy-specific drugs)
✓Exclusion of other hypersomnia causes (sleep apnea, insufficient sleep, medications)

Commonly Confused Codes

•G47.411 (Narcolepsy with cataplexy): Type 1 narcolepsy; includes cataplexy episodes
•G47.10 (Hypersomnia, unspecified): nonspecific; narcolepsy has specific diagnostic criteria
•G47.429 (Narcolepsy in conditions classified elsewhere, without cataplexy): use for secondary narcolepsy
•G47.11-G47.19 (Idiopathic hypersomnia): excessive sleep without narcolepsy sleep architecture on MSLT
•G47.31-G47.39 (Sleep apnea): respiratory cause of excessive daytime sleepiness

Child Codes

G47.411Narcolepsy with cataplexy

G47.419Narcolepsy without cataplexy

Code Hierarchy

└G47Sleep disorders └G47.4Narcolepsy and cataplexy └G47.41Narcolepsy └G47.419Narcolepsy without cataplexy

└G47.419Narcolepsy without cataplexy

G47.419 ICD-10-CM Code: Narcolepsy without cataplexy

HCC Buddy Code Card

G47.419

Is G47.419 an HCC code?

HCC Category Mapping

MEAT Criteria for G47.419

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What This Code Means

Coding Tips

Clinical Significance

Documentation Requirements

Commonly Confused Codes

Child Codes

Code Hierarchy

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