Background |  Areas of Current Investigation |  Selected Resources


Logical Observation Identifiers, Names, and Codes (LOINC) is a standard that facilitates the exchange and pooling of results, such as laboratory tests or vital signs, for clinical care, outcomes management, and research. LOINC is considered a universal coding system, enabling health care organizations to map (or link) their local codes to LOINC codes for transmission in clinical messages to payers, regulators, and other health care organizations. LOINC codes are based on a six-part name, which means that codes are unique not just to the component (e.g., Hemoglobin) but also to the specimen (e.g., whole blood) and the other parts that define a distinct result.

The LOINC standard is maintained and distributed freely by the Regenstrief Institute with support from the U.S. National Library of Medicine (NLM). LOINC has been endorsed by the American Clinical Laboratory Association and the College of American Pathologists. It is also a part of the NLM's Unified Medical Language System (UMLS), and it has been adopted by several Federal agencies including the Centers for Disease Control and Prevention (CDC), the Department of Defense (DoD), and the Department of Veterans Affairs.

The Regenstrief LOINC Mapping Assistan (RELMA) is a Windows-based application that assists organizations in translating their local institution codes to the LOINC standard. The tool is available for download, free of charge, at the LOINC Web site.

Workshops on LOINC and how to use the RELMA tool are usually offered at the semiannual public meetings sponsored by the Regenstrief Institute. Visit the LOINC Web site to learn when and where the next meeting will be held.

Areas of Current Investigation

LOINC is one of a suite of designated standards for use in U.S. Federal Government systems for the electronic exchange of clinical health information and is also a required standard in interoperability specifications of the U.S. Healthcare Information Technology Standards Panel.

Mapping an institution's entire code set can be time-consuming and costly. Two recent studies suggest a practical approach to more quickly achieving translation between local and LOINC codes. In the first study, investigators examined real-world clinical laboratory results sent from five hospitals in the Indianapolis area. During a 12-month period, 4,000 codes accounted for almost 49 million clinical results. Of the total codes identified, 80 (2 percent) codes accounted for 80 percent of the results, and 784 (19 percent) codes account for 99 percent of the results. These results suggest that organizations can reduce the time and effort needed to map local codes to LOINC by initially focusing on a subset of high-volume transaction codes. This may lead to faster adoption and use of standardized LOINC codes for the exchange of clinical results within and between disparate health care organizations. A similar approach was used in a second study conducted in Tennessee.

Selected Resources

LOINC, a Universal Standard for Identifying Laboratory Observations: a 5-year Update
Author(s): McDonald CJ, Huff SM, Suico JG, Hill G, Leavelle D, Aller R, Forrey A, Mercer K, DeMoor G, Hook J, Williams W, Case J, Maloney P
Source: Clin Chem. 2003 Apr;49(4):624-33.
Summary: The Logical Observation Identifier Names and Codes (LOINC) database provides a universal code system for reporting laboratory and other clinical observations. Its purpose is to identify observations in electronic messages such as Health Level Seven (HL7) observation messages, so that when hospitals, health maintenance organizations, pharmaceutical manufacturers, researchers, and public health departments receive such messages from multiple sources, they can automatically file the results in the right slots of their medical records, research, and/or public health systems. For each observation, the database includes a code (of which 25,000 are laboratory test observations), a long formal name, a "short" 30-character name, and synonyms. LOINC codes are being used by large reference laboratories and federal agencies, and are part of the Health Insurance Portability and Accountability Act (HIPAA) attachment proposal. Laboratories should include LOINC codes in their outbound HL7 messages so that clinical and research clients can easily integrate these results into their clinical and research repositories.

Last Modified: March 2016