On June 15, 2018, FDA issued Guidance on Logical Observation Identifiers Names and Codes (LOINC) for in vitro diagnostic (IVD) tests. Since information from IVD tests comprises a significant portion of electronic health records (EHRs), FDA hopes that a consistent and uniform standard for coding IVD test results will promote medical device interoperability overall.

LOINC, owned and developed by the Regenstrief Institute, helps laboratories code IVD and other test results. For IVD tests, unique LOINC numerical codes identify the type of test based on attributes such as component, property, time, system, scale, and method. LOINC is the most widely used and recognized coding system for clinical laboratories, EHRs, and certain government agencies. FDA, however, currently limits its recognition of LOINC only to IVD tests and publishes a list of other LOINC classes not recognized by FDA.

FDA does not mandate the use of LOINC but recognizes the need for a consensus standard for coding IVD tests, and specifically acknowledges LOINC’s utility to that end. Medical device manufacturers may include LOINC codes in labeling so long as the information is accurate, consistent with FDA-approved indications for the device, and compliant with other FDA requirements. FDA states that it will not perform premarket review of LOINC codes.

Manufacturers may disseminate LOINC codes through printed labeling, or other external locations (such as manufacturers’ websites) that list LOINC codes for IVD tests. Inclusion of a LOINC code for an unapproved indication may be evidence of a new intended use or adulterating or misbranding of the device. On the other hand, manufacturers who provide or identify the need for new LOINC codes in response to unsolicited specific requests by clinical laboratories may do so without risk of FDA construing the response as evidence of intent to use the device for an unapproved indication. This Guidance does not change existing requirements for new premarket notification submissions (510(k)) or new Premarket Approval Applications.

While FDA does not recommend any specific format for distributing LOINC codes, FDA strongly encourages the development of an FDA-recognized consensus standard so that laboratories will be able to efficiently adopt new LOINC codes, update and change existing LOINC codes, and maintain a local database. FDA encourages manufacturers to keep abreast of developments and evolving standards in this area.

Readers are encouraged to read the Guidance, also available on FDA’s website.