Fever presenting with conditions classified elsewhere

This code indicates a fever that is a symptom of, or associated with, another underlying medical condition. It is used when the fever itself is not the primary diagnosis but rather a manifestation of a separately classified disease process.

Apply this code when documentation clearly states fever as a presenting symptom, and the definitive underlying cause of the fever is also identified and coded. Examples include fever due to pneumonia, urinary tract infection, or influenza, where the infection itself is coded first.

• Always sequence the definitive diagnosis for the underlying condition first, with this code as a secondary diagnosis.
• Do not use this code if the fever is unspecified, of unknown origin, or the primary reason for the encounter without a definitive underlying cause identified.
• Distinguish from codes for fever of unknown origin (e.g., R50.81) or other specific types of fever when the cause is not yet determined or is the focus of the encounter.