Information about LOINC and RELMA
LOINC segments
LOINC is a set of terms (terminology) for universal, globally unique identification of medical examinations. The terminology was originally developed by the Regenstrief Institute for laboratory tests, but has been expanded over time to include clinical observations, medical document types and questionnaires/questions. The four LOINC segments have the following proportions of the code system (as of 2021):
- Laboratory (approx. 61 %)
- Clinical (approx. 26 %)
- Attachments (approx. 1 %)
- Surveys (approx. 12 %)
Structure of a LOINC term
To accurately identify an examination or observation, a LOINC term consists of six axes (dimensions):
- Component (parameter or analyte)
- Property (measurand)
- Time (time or interval at which the measurement or observation occurred)
- System (observed system - sample material, body part or environment)
- Scale (data type in which the result of the measurement or observation is specified)
- Method (optional: method by which the measurement or observation took place)
Examples:
| LOINC NUM | Component | Property | Time ASPCT | System | Scale | Method | Class |
|---|---|---|---|---|---|---|---|
| 738-5 | Macrocytes | PrThr | Pt | Bld | Ord | Mikroscopy.light | HEM/BC |
| 8080-4 | Myelin Ab.IgG | ACnc | Pt | Ser | Qn | SERO | |
| 9453-2 | Histidine | SCnc | Pt | CSF | Qn | CHEM | |
| 56680-2 | Glutamine/ Creatinine | Ratio | 24H | Urine | Qn | CHEM |
For the Fully specified name (FSN), the information of the 6 axes is separated by colons:
Lymphocytes:NCnc:Pt:Bld:Qn:Flow cytometry
For the German-language terms, the Long Common Name (LCN) was introduced as a display name with Release 2.72. The LCN contains the essential information of a LOINC identifier in the common grammar and with typical, generally understandable language usage.
Examples of the German Long Common Name:
| LOINC-Kode | Long common name |
|---|---|
| 56680-2 | Glutamin/Kreatinin [Verhältnis] in 24-Stunden-Urin |
| 738-5 | Makrozyten [Nachweis] in Blut mit Lichtmikroskopie |
| 8080-4 | Myelin-IgG-Antikörper [Einheiten/Volumen] in Serum |
| 9453-2 | Histidin [Mol/Volumen] in Zerebrospinalflüssigkeit |
There is a lot of additional information (attributes) in the LOINC table that is not part of the LOINC term. These help the user to correctly assign or interpret LOINC codes. These are for example:
- Class - Grouping of examinations
- Status - Status of the LOINC code (Active, Discouraged, Deprecated, Trial)
- Classtype - Identification of LOINC segment membership
- Related Names2 - Synonyms of the terms and keywords
- Order_Obs - Identifies whether the order is a requirement or an observation
- Example Units - Example units of measure
- Example_UCUM units - Example units of measure with UCUM notation
LOINC, UCUM and SNOMED CT for the structured exchange of laboratory and clinical observations
Both LOINC and UCUM are maintained and published by the Regenstrief Institute. LOINC is used to describe a requirement or clinical phenomenon that can be measured or observed. UCUM enables structured representation and electronic transmission of quantitative results by providing technically uniform and scalable units of measurement and convention units.
SNOMED CT is used for qualitative result coding.
The Regenstrief Institute and SNOMED International work closely together. Further information can be found below:
Information from SNOMED International on sharing SNOMED CT and LOINC
Information from Regenstrief Institute on collaboration with SNOMED International
Getting to know LOINC better (further information material)
To learn more about LOINC, we recommend the following websites:
Search and download LOINC codes
Searching LOINC codes
There are several ways to find the correct LOINC code:
- Static URL - For each LOINC code, the associated information can be retrieved directly in the browser using the following scheme: https://loinc.org/[LOINC code].
- LOINC Search - After free registration you can use the LOINC Search. This allows you to search for "LOINC" codes, "Parts", "Answer-Lists" or "Groups". Additional filters can be used to further customise the search.
https://loinc.org/search/ (after free registration) - Search in RELMA for Download - Download can also be searched for in RELMA. A search with extended search functions is possible via RELMA, e.g. a setting according to a specific language or a hierarchical search.
https://loinc.org/downloads/relma/ (after free registration)
Download LOINC codes
The Regenstrief Institute provides LOINC, RELMA and additional information in a download area. This is accessible after free registration. The data is provided in different formats.
Technical provision for software applications
An interface to FHIR is available for software applications.
Information on the automated retrieval of terms via the FHIR server from the Regenstrief Institute can be found on the following website:
RELMA (Regenstrief LOINC Mapping Assistant)
To research LOINC codes and assist in mapping other, mostly proprietary, coding systems for LOINC content, the Regenstrief Institute supplies the Regenstrief LOINC Mapping Assistant (RELMA) tool.
Features of RELMA:
- Research of LOINC codes, terms, synonyms.
- Setting of other languages
- Mapping support
- Hierarchical grouping of terms
Regenstrief LOINC Mapping Assistant (RELMA) (after free registration)
LOINC Community
LOINC is used in many areas of work and is continuously developed by Regenstrief. In many institutions and regions of the world, LOINC is now used as a standard and translated into many languages.
An overview of the "LOINC Adopters" can be found on the following website:
The further development of LOINC takes place together with international expert groups, especially in the areas of laboratory and clinic. Further expert groups will be established for specific topics. Interested parties can apply for membership in these expert groups.
Furthermore, there are open topic-specific user forums where current topics can be discussed.
The Regenstrief Institute regularly publishes information on current developments. To stay informed, it is possible to sign up for a mailing list or newsletter:
The Regenstrief Institute hosts bi-annual events.
For the latest information on events, please visit the following website:Events on LOINC of the Regenstrief Institute