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Logical Observation Identifiers Names and Codes (LOINC) is a standardized coding system for laboratory and clinical tests, procedures, observations, surveys, and corresponding results.
All LOINC source information is obtained from the following:
1. LOINC Website (https://loinc.org/downloads/) that is supported by the Regenstrief Institute:
2. The National Library of Medicine (NLM) Website:
3. Ordered List ItemLOINC Users” Guide:
“long_common_name” field values are considered to be preferred terms for concept names “consumer_name”, “shortname” and “relatednames2” field values reside in the concept synonym table
All LOINC Concepts are Standard Concepts, while Concepts of the Source LOINC Class, LOINC Hierarchy are Classification 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 |
Concepts in the LOINC vocabulary are assigned Concept Class as following:
| Source | Resourced | Concept Class | Description |
|---|---|---|---|
| LOINC | CLASSTYPE=1 | Lab Test | The Universal Lab Order Codes Value Set contains the most frequent lab orders |
| CLASSTYPE=2 | Clinical Observation | Anything that can be tested, measured, or observed about a patient without removing a specimen | |
| CLASSTYPE=3 | Claims Attachment | Information necessary to adjudicate claims for ambulance, rehabilitation, or emergency room services | |
| CLASSTYPE=4 | Survey | Set of questions on a survey or form | |
| CLASS | LOINC Class | Similar to the Concept Classes of each LOINC Concept, but more detailed and hierarchical | |
| LOINC Hierarchy | CODE | LOINC Hierarchy | Similar to LOINC Class, but separate hierarchical system |
| LOINC Answer | AnswerStringID | Answer | Observation result value as an answer to a LOINC Concept |
LOINC Concepts can have a Measurement or Observation Domain. This is assigned as following:
| 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 are defined within LOINC and between LOINC and CPT and LOINC and SNOMED:
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% as of late 2015) are currently mapped. Also, note that some of the mappings seem to confuse the testing for drugs with the drugs themselves.
These relationships are defined as “LOINC - CPT4 eq” between LOINC Lab Test Concepts and SNOMED Concepts. Note that only a small franction (2% as of late 2015) are mapped.
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.