G47.421
Narcolepsy in conditions classified elsewhere with cataplexy
G47.421 (also written G47421) is a billable ICD-10-CM diagnosis code for narcolepsy in conditions classified elsewhere with cataplexy. It is part of the FY2027 code set, effective October 1, 2026. It is one of the 43 codes in category G47 (Sleep disorders). The Alphabetic Index lists it under 1 entry. Its coding notes include a Code first instruction and 12 Excludes2 entries.
Code first
If the underlying condition listed here is present and known, sequence it first.
- underlying condition
Excludes2
Not included here. Both codes may be reported if the patient has both conditions.
Also from chapter/block level (8 notes)
- certain conditions originating in the perinatal period (P04-P96)
- certain infectious and parasitic diseases (A00-B99)
- complications of pregnancy, childbirth and the puerperium (O00-O9A)
- congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
- endocrine, nutritional and metabolic diseases (E00-E88)
- injury, poisoning and certain other consequences of external causes (S00-T88)
- neoplasms (C00-D49)
- symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)
Care settings
How CMS programs treat this code. These are CMS claim edits and list entries, not coverage or eligibility rules.
Hospice: not accepted as primary
Not accepted as the principal diagnosis on a hospice claim (bill types 081x and 082x). The Integrated OCE returns an edit for this code.
Reason: Manifestation code. Report the underlying condition first (see the Code first note).
Alphabetic Index terms
Terms the official Alphabetic Index lists for this code. 1 entry