HDn

HDN is an acronym that can refer to several different concepts depending on context. The most widely recognized meanings are in medicine and aviation, with additional uses in information technology and other fields.

In medicine, HDN stands for hemolytic disease of the newborn. This condition occurs when maternal antibodies cross the placenta and attack fetal red blood cells, most commonly due to Rh(D) incompatibility but also related to ABO or other antigen mismatches. The destruction of red blood cells can cause fetal or neonatal anemia and hyperbilirubinemia, leading to jaundice and, in severe cases, hydrops fetalis. Prevention and treatment include administering Rho(D) immune globulin to Rh-negative pregnant individuals to prevent sensitization, and postnatal care that may involve phototherapy for jaundice and, in severe cases, exchange transfusion or intrauterine transfusion.

HDN is also the IATA airport code for Yampa Valley Airport, located in Hayden, Colorado, United States. The airport serves the Steamboat Springs area and surrounding communities, providing domestic air service and connections to larger hubs.

Beyond medicine and aviation, HDN is used as an acronym in various domains, including information technology and communications. In vendor literature or project documentation, it may denote terms such as High-Density Network or Homogeneous Data Network, among others. There is no single, universally accepted definition for these usages, and meanings are highly context-dependent.