R50.81 Fever presenting with conditions classified elsewhere
Billable ICD-10-CM code, FY2026.
Code first
underlying condition when associated fever is present, such as with:
leukemia (C91-C95)
neutropenia (D70.-)
sickle-cell disease (D57.-)
Applies from R50 Fever of other and unknown origin
Excludes1 (never code together)
chills without fever (R68.83)
febrile convulsions (R56.0-)
fever of unknown origin during labor (O75.2)
fever of unknown origin in newborn (P81.9)
hypothermia due to illness (R68.0)
malignant hyperthermia due to anesthesia (T88.3)
puerperal pyrexia NOS (O86.4)
MS-DRG index
Defines the logic of DRG(s) 864 in MDC 18.
Approximate ICD-9-CM (GEMs)
780.61 Fever presenting with conditions classified elsewhere
Medicare Code Edits (MCE v43.1 (April 2026))
Manifestation codes as principal diagnosis: Manifestation codes describe the manifestation of an underlying disease, not the disease itself, and are not allowed as principal diagnosis.
Code annotations containing back-references to R50.81
Back-references to R50.81
Use Additional: D57 Sickle-cell disorders ("code for any associated fever (R50.81)")
Use Additional: D70 Neutropenia ("fever (R50.81)")
Diagnosis Index entries for R50.81
Fever (inanition) (of unknown origin) (persistent) (with chills) (with rigor) › due to › conditions classified elsewhere