12.5 LOINC term names in HL7 messages

Messaging standards like HL7 typically use a triplet \^\^\ for fields that contain coded entries, such as the OBX-3 Observation Identifier field. Given that LOINC now produces at least three names for each term (i.e., the six-part Fully-Specified Name, Short Name, and Long Common Name), users have wondered which LOINC name they should use in the \ part of that field (or the equivalent displayName attribute in HL7 V3).

Regenstrief and the LOINC Committee assert that best practice is to send the Long Common Name to accompany the LOINC code in messaging. The Long Common Name is complete, unambiguous, and the most understandable LOINC description for human readers.

We recognize that there may still be some information systems today that are not able to accommodate the character length of the Long Common Name. We strongly recommend updating such systems to accommodate longer names. The LOINC Short Name is smaller in size, but not very human friendly and is not populated for all LOINC terms. (We are working to improve on both of these issues). Using the Fully-Specified Name (e.g. a colon-separated aggregate of the six Part name) is generally not recommended because they are not as human friendly and contain more instances of ‘reserved characters’ like “^” and “&”, which would need to be properly escaped in the message.

Furthermore, we recommend the simultaneous communication of the sender’s local code and local name (in addition to the LOINC code and name) as allowed in the messaging structure to facilitate debugging and detection of mis-mappings. Laboratory local codes are often required to be sent by the performing laboratory to meet CLIA (U.S) and laboratory accreditation regulatory requirements in many countries.

It is also worth noting that use of the Long Common Name in messaging does not dictate which test name is displayed in user interfaces to clinicians. There are often regulatory requirements and/or local policies that influence what is shown to clinicians. Many of the implementations around the world using LOINC have a local “interface name” that users see. LOINC is working in the background.