D81

D81 is a designation used across multiple unrelated systems to label a specific entry or category. Because it appears in different contexts, its meaning cannot be inferred without domain information.

In medical coding, D81 is a code in ICD-10-CM used to classify immune system disorders. It sits within a broader block that covers immune-related conditions, and the precise disorder is identified by subcodes added to the D81 base (for example, D81.0, D81.1, and so on) in the official coding manual. The ICD-10-CM system is used by clinicians and health services for diagnosis documentation and billing, with periodic updates that can adjust code assignments and groupings.

In transportation, D81 may appear as a road designation in certain countries that use a D-prefix for regional or departmental routes. Such numbers are local to a particular jurisdiction and can change through renumbering, construction, or reclassification. When encountered, D81 typically points to a specific local road or route within a department or region rather than representing a nationwide highway.

In other domains, D81 can be used as a catalog or model identifier—found in product catalogs, library classifications, or technical specifications—where the same code may have different meanings depending on the system in which it is recorded. As with other alphanumeric identifiers, accuracy depends on consulting the relevant authority or documentation for the exact context.

See also: the broader uses of the D80–D89 coding range in ICD-10-CM and the general practice of regional road numbering schemes.