Observational Health Data Sciences and Informatics

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 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

3. LOINC Users' Guide:

• Manual table of LOINC Classes

• 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.

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:

Relationships are defined within LOINC and between LOINC and CPT, and LOINC and SNOMED:

A purpose of Internal LOINC relationships is to build a LOINC Hierarchy, which makes it easier to sort and browse the database.

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.

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.

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.