F51.11 is not a CMS-HCC payment code. MEAT criteria · RAF Calculator · HCC coding software

ICD-10-CM Code View

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Code lookupF51.11

Effective periodFY2026 Apr Update (Apr 1-Sep 30)

FY 2026 Apr update / Mental, Behavioral and Neurodevelopmental disorders (F01-F99) / Behavioral syndromes associated with physiological disturbances and physical factors (F50-F59)

F51.11

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

Primary hypersomnia

A condition where a person sleeps excessively during the day despite getting adequate nighttime sleep, without an identifiable medical cause.

Overview Risk Models Code Book Documentation Audit Notes Edition comparison

CMS-HCC V28

N/A

—

Not risk-adjusted for this model/period.

Not mapped

CMS-HCC V24

Historical

Not used for standard CY2026 Medicare Advantage payment. Select a historical period to review V24.

Not used for CY2026 payment

ACA/HHS

N/A

—

Not risk-adjusted for this model/period.

Not mapped

ESRD/PACE

N/A

—

Not risk-adjusted for this model/period.

Not mapped

RXHCC

N/A

—

Not risk-adjusted for this model/period.

Not mapped

Code Book Path

Official

F51Sleep disorders not due to a substance or known physiological condition F51.1Hypersomnia not due to a substance or known physiological condition F51.11Primary hypersomnia

Inclusion Terms

Official

No inclusion terms are included in this display for F51.11. Check the code and parent instructions in the Code Book.

Excludes 2

Official

symptoms, signs and abnormal clinical laboratory findings, not elsewhere classified (R00-R99)Inherited from F01-F99, F51, F51.1
organic sleep disorders (G47.-)Inherited from F01-F99, F51, F51.1
alcohol related hypersomnia (F10.182, F10.282, F10.982)Inherited from F01-F99, F51, F51.1
drug-related hypersomnia (F11.182, F11.282, F11.982, F13.182, F13.282, F13.982, F14.182, F14.282, F14.982, F15.182, F15.282, F15.982, F19.182, F19.282, F19.982)Inherited from F01-F99, F51, F51.1
hypersomnia NOS (G47.10)Inherited from F01-F99, F51, F51.1
hypersomnia due to known physiological condition (G47.10)Inherited from F01-F99, F51, F51.1
idiopathic hypersomnia (G47.11, G47.12)Inherited from F01-F99, F51, F51.1
narcolepsy (G47.4-)Inherited from F01-F99, F51, F51.1

Related Codes

Official

F51.12Insufficient sleep syndrome F51.13Hypersomnia due to other mental disorder F51.19Other hypersomnia not due to a substance or known physiological condition

Includes

Official

disorders of psychological developmentInherited from F01-F99

Excludes 1

Official

No Excludes 1 notes are included in this display for F51.11. Check the code and parent instructions in the Code Book.

Code First

Official

No Code First sequencing instructions are included in this display for F51.11. Check the code and parent instructions in the Code Book.

Use Additional

Official

No Use Additional Code instructions are included in this display for F51.11. Check the code and parent instructions in the Code Book.

Code Also

Official

No Code Also instructions are included in this display for F51.11. Check the code and parent instructions in the Code Book.

Buddy Documentation Tip

HCC Buddy guidance

Distinguish from narcolepsy (G47.4) which involves sudden sleep attacks and cataplexy

Document that excessive daytime sleepiness is not due to sleep apnea or other sleep disorders

Current with CMS: FY2026 ICD-10-CM Apr 1 update (effective Apr 1 – Sep 30, 2026) · CMS-HCC V28, 100% phased in for payment year 2026. FY2027 code set already staged for October 1, 2026. How HCC Buddy stays current →

Is F51.11 an HCC code?

No. F51.11 is a billable ICD-10-CM code with no mapping under the current CMS-HCC V28 community payment model, and none under the ESRD, Part D RxHCC, or HHS-HCC models.

Code: F51.11
Description: Primary hypersomnia
HCC (V28): No CMS-HCC V28 mapping
RAF reference coefficient: —
Billable: Yes
Payment year: 2026

Coder workflow notes

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What This Code Means

F51.11 is the ICD-10-CM diagnosis code for primary hypersomnia. A condition where a person sleeps excessively during the day despite getting adequate nighttime sleep, without an identifiable medical cause. F51.11 sits in the ICD-10-CM chapter for mental, behavioral and neurodevelopmental disorders (f01-f99), within the section covering behavioral syndromes associated with physiological disturbances and physical factors (f50-f59).

F51.11 is a billable ICD-10-CM code, but no current CMS-HCC V28 community payment mapping is shown, and none under the ESRD, Part D RxHCC, or HHS-HCC models. Do not assign risk adjustment value from this page when no source-backed mapping is shown; verify the applicable model and payment year.

Distinguish from narcolepsy (G47.4) which involves sudden sleep attacks and cataplexy.

HCC Buddy maintains structured V28 and V24 mapping, source-labeled coefficient references, and MEAT documentation criteria for F51.11 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Distinguish from narcolepsy (G47.4) which involves sudden sleep attacks and cataplexy
•Document that excessive daytime sleepiness is not due to sleep apnea or other sleep disorders