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Table of Contents
LOINC
Logical Observation Identifiers Names and Codes (LOINC) is a standardized coding system for laboratory and clinical tests, procedures, observations, surveys, and corresponding results.
Sources
All LOINC source information is obtained from the following:
1. LOINC Website that is supported by the Regenstrief Institute:
- LOINC Table Core (Observations and Measurements)
- LOINC Answers
- LOINC Multiaxial Hierarchy
- LOINC Document Ontology
- LOINC Panels and Forms
- LOINC Groups
- LOINC to SNOMED mapping
- LOINC Replacement Mapping
2. The National Library of Medicine (NLM) Website:
- LOINC To CPT Mapping
- Manual table of LOINC Classes
Concept Names
- Values of a “long_common_name” field are considered to be preferred terms for concept names.
- Values of “consumer_name”, “shortname” and “relatednames2” fields reside in the concept synonym table as synonyms.
Standard Concepts
| Source Concept Type | Standard Concept |
|---|---|
| LOINC Observations and Measurements | Standard |
| LOINC Answers | Standard |
| LOINC Hierarchy | Classification |
| LOINC Classes | Classification |
| LOINC Categories | Classification |
| LOINC Groups | Classification |
Domains and Concept Classes
LOINC Concepts are located in such domains as “Observation”, “Measurement”, or “Meas Value”.
Previously all concepts with a LOINC property of “classtype” with values “1” and “2” were considered to be Measurements. However, an initial analysis of such extended LOINC properties as “property”, system”, “scale_type”, “class”, “method_typ”, “definitiondescription” and “survey_quest_text” revealed that the LOINC domain distribution can be more accurate if used the combinations of LOINC properties. In turn, the Concept Class definition is interconnected with a defined Domain.
So, they were assigned pursuant to the following criteria:
| Source | Depending on | Domain |
|---|---|---|
| LOINC | CLASSTYPE=1 or 2 | Measurement |
| CLASSTYPE=3 or 4 | Observation | |
| LOINC Hierarchy | Concept_code>'LP76352-1' | Observation |
| Concept_code>='LP76352-1' | Measurement | |
| LOINC Class | Manual | Observation or Measurement |
| LOINC Answer | Meas Value |
Relationships
Relationships are defined within LOINC and between LOINC and CPT, and LOINC and SNOMED:
1. Internal LOINC relationships
A purpose of Internal LOINC relationships is to build a LOINC Hierarchy, which makes it easier to sort and browse the database.
| Relationship | From | To |
|---|---|---|
| Is a | Descendant LOINC Class | Ancestor LOINC Class |
| Is a | LOINC Group | LOINC Group Category |
| Is a | LOINC Measurement or Observation | LOINC Class |
| Is a | LOINC Measurement or Observation | LOINC Group |
| Is a | Descendant LOINC Measurement or Observation | Ancestor LOINC Measurement or Observation |
| Panel contains | LOINC Panel | LOINC Measurement or Observation |
| Has Answer | LOINC Question | LOINC Answer |
| Has type of service | LOINC Measurement or Observation | LOINC concept indicating a Type of Service (Document Ontology) |
| Has subject matter | LOINC Measurement or Observation | LOINC concept indicating a Subject Matter Domain (Document Ontology) |
| Has role | LOINC Measurement or Observation | LOINC concept indicating a Role (Document Ontology) |
| Has setting | LOINC Measurement or Observation | LOINC concept indicating a Setting (Document Ontology) |
| Has kind | LOINC Measurement or Observation | LOINC concept indicating a Kind of Document (Document Ontology) |
| Concept replaced by | Updated LOINC concept | New LOINC concept |
| Reverse Relationship | From | To |
|---|---|---|
| Subsumes | Ancestor LOINC Class | Descendant LOINC Class |
| Subsumes | LOINC Group Category | LOINC Group |
| Subsumes | LOINC Class | LOINC Measurement or Observation |
| Subsumes | LOINC Group | LOINC Measurement or Observation |
| Subsumes | Ancestor LOINC Measurement or Observation | Descendant LOINC Measurement or Observation |
| Contained in panel | LOINC Measurement or Observation | LOINC Panel |
| Answer of | LOINC Answer | LOINC Question |
| Type of service of | LOINC concept indicating a Type of Service (Document Ontology) | LOINC Measurement or Observation |
| Subject matter of | LOINC concept indicating a Subject Matter Domain (Document Ontology) | LOINC Measurement or Observation |
| Role of | LOINC concepts indicating a Role (Document Ontology) | LOINC Measurement or Observation |
| Setting of | LOINC concepts indicating a Setting (Document Ontology) | LOINC Measurement or Observation |
| Kind of | LOINC concepts indicating Kinds of Document (Document Ontology) | LOINC Measurement or Observation |
| Concept replaces | New LOINC concept | Updated LOINC concept |
2. LOINC to SNOMED relationships
These relationships are defined as “LOINC - SNOMED eq” between “LOINC Hierarchy” Concepts and SNOMED Concepts representing the entity that is measured. Note that only a small fraction (1%) is currently mapped. Also, note that some of the mappings seem to confuse the testing for drugs with the drugs themselves.
3. LOINC to CPT relationships
These relationships are defined as “LOINC - CPT4 eq” between LOINC Lab Test Concepts and SNOMED Concepts. Note that only a small fraction (2%) is mapped.
Hierarchy
All internal “Is a” and “Panel contains” relationships participate in the creation of the CONCEPT_ANCESTOR table, creating an internal hierarchy within LOINC not connected to the larger Measurement or Observation Domain space.