ICD-10-CM 2027
ICD-10 code for primary hypersomnia
From the official ICD-10-CM alphabetic index entry “Hypersomnia (organic) › primary”. Page updated September 29, 2026.
About coding primary hypersomnia
The ICD-10-CM code for primary hypersomnia is F51.11 (Primary hypersomnia).
Within F51.1 (hypersomnia not due to a substance or known physiological condition), F51.11 is specifically for primary hypersomnia. Related codes cover insufficient sleep syndrome (F51.12), hypersomnia due to other mental disorder (F51.13) and other hypersomnia not due to a substance or known physiological condition (F51.19).
It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.
In MS-DRG v44.0, it is part of the grouping logic for DRG 887 (Other Mental Disorder Diagnoses, relative weight 1.1139), in MDC 19 (Mental Diseases and Disorders), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.
Common questions about primary hypersomnia ICD-10 codes
What is the ICD-10 code for primary hypersomnia?
- F51.11 — Primary hypersomnia.
Is F51.11 billable?
- Yes. F51.11 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can F51.11 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict F51.11 as a principal diagnosis.
Is F51.11 a CC or MCC?
- No. F51.11 is neither a CC nor an MCC under MS-DRG v44.0.