Regenstrief InstituteSNOMED International

Frequently Asked Questions

When is the first production release of the LOINC Ontology expected?

Feedback for the preview from the community is expected to continue to run through Q1 2024. The date of the first release will be driven by the extent of the feedback and any changes necessary to the approach. However, we hope that a first production release will be published during 2024.

Where will I go to download the preview release?

Go to where you can register to download the preview, as well as receive any updates on the progress.

How do I sign up to get news about the LOINC Ontology or express interest in collaborating on the work?

Go to where you can register to receive updates on the progress and register your interest in being involved in collaborating on the LOINC SNOMED CT Interoperability Solution.

How can I browse the LOINC Ontology?

Go to From there you have a few options for viewing the content.

  • The Search tab features a search box where a text string, LOINC term, or SNOMED CT concept id can be entered. The LOINC concepts will be most easily found by restricting the search results to the “observable entity” hierarchy, which is an option in the “Filter results by Semantic Tag” area. Click on a concept in the search results to view more information about the concept in the “Concept Details” tab, including additional descriptions, SNOMED CT concept identifier, LOINC term code, attributes given to a concept, and its place in the hierarchy including parent(s) and children concepts, if any. Note: to view the concepts after classification, make sure to click the “Inferred” view on the right hand side of the screen.

  • The Taxonomy tab shows a clickable hierarchical structure of the content. Click on a concept in the search results to view more information about the concept in the “Concept Details” tab,

  • The Expressions Constraint Queries tab allows for ECL queries to be performed on the content to retrieve a set of concepts that fit criteria. The ECL Query Builder functionality can be used, or a query can be manually entered into the box and then Execute will start the query. An example of a query that can be entered is one to retrieve all observable concepts that have a Component of an antibody or some type of antibody:

    << 363787002 |Observable entity (observable entity)| : 246093002 |Component (attribute)| = << 68498002 |Antibody (substance)|
  • This returns over 4000 results. Additional ECL query examples are listed in the appendix of the preview documentation.

What are the next LOINC terms to be modelled using the SNOMED CT observable entity model? Will it be the rest of the laboratory LOINC terms or will you consider linking any of the LOINC clinical terms to the SNOMED concept model?

With the publication of the preview, we hope to get further feedback from the community to input into the decision of where we go next. While we have been able to model almost 24,000 LOINC terms, there are more to go. However, there are other domains and content types that may be of more interest to the community. These include panels, answer lists, and more.

Is it expected that all of LOINC will eventually be included in the LOINC Ontology?

While we aim to include as much of LOINC as is possible, there may be content that cannot be included due to the differences between the existing LOINC and SNOMED CT models and editorial guidelines.

When requesting a new LOINC Code, does it mean that a new equivalent SNOMED code and vice versa should be requested as well?

When requesting a new LOINC code, and if the request is approved, the related content will eventually be modeled in the LOINC Ontology and in doing so, a SNOMED CT identifier will be assigned at that point.

Who is going to evaluate the creation of the new code in LOINC or in SCT if it doesn’t exist in one or the other but would become a code in the extension?

The teams from Regenstrief and SNOMED International will work together to evaluate the validity of new content requests in both the LOINC and SNOMED CT contexts. The content in the LOINC Ontology is a direct representation of content in LOINC and is owned by Regenstrief, therefore any final decision to create a new LOINC code will be made by Regenstrief. Similarly, content in the SNOMED CT International Edition is owned by SNOMED International and if content is only relevant for SNOMED CT and not LOINC, it would be created following existing processes.

Is there going to be a request process combined for both LOINC and SCT?

There will not be a combined request process, but both organizations will confer with the other when content related to the collaborative work is requested.

Is there a document that reflects what has been done, and what the plan is going forward in the short term (next release) and long-term (one year forward)?

The Release Notes document provides background in the work that has been done to produce the preview.

Do I need access to SNOMED CT to use the LOINC Ontology?

Yes, you will need to have access to the SNOMED CT International Edition to make the best use of the LOINC Ontology. The SNOMED CT International Edition can be downloaded from your country’s National Release Center if you are in a SNOMED International Member Country. If you are in a non-Member country, please register with SNOMED International,

Do I need a SNOMED CT licence to use the LOINC Ontology?

You do not need a SNOMED CT licence to use the LOINC Ontology and any content within it as this is covered under the existing LOINC license.

What about translations and the LOINC Ontology? How do I translate what is there and can I use existing LOINC translations?

We are working on a process to handle translations.

How often is the LOINC Ontology going to be updated?

After the first production release of the LOINC Ontology, we expect to keep that up to date with each release of LOINC and the related version of the SNOMED CT International Edition at the time of release.

Will there be a map between the ontology and LOINC release files?

As part of the RF2 release package of the LOINC Ontology, each concept has an associated SNOMED CT concept identifier and existing LOINC code. These are provided in the RF2 alternative identifier file, where each LOINC code is linked to its related SNOMED CT concept identifier.

Why are the fully specified name (FSN) and preferred term (PT) of some LOINC extension concepts inconsistently named?

The FSN and PT of the LOINC extension concepts are automatically created based on the terming of the SNOMED CT concepts used in the modeling of the LOINC extension concepts. Therefore, issues or inconsistencies in the terming of the SNOMED CT content will appear in the FSN and PT of the LOINC extension concepts. This legacy SNOMED CT content that does not adhere to current editorial guidelines will be updated as resources allow.