Final answer:
LOINC codes are found in the UMLS Metathesaurus, which is a comprehensive database that integrates multiple biomedical vocabularies and coding standards to facilitate interoperability between healthcare computer systems.
Step-by-step explanation:
The question asks where one would find LOINC (Logical Observation Identifiers Names and Codes) in the UMLS (Unified Medical Language System). LOINC is a database and universal standard for identifying medical laboratory observations. The correct answer is C. Metathesaurus.
LOINC codes are part of the UMLS Metathesaurus, a large, multi-purpose, and compiled database of biomedical terms that interrelates various vocabularies and standards, including those used for electronic health records and health information exchange. The Metathesaurus is one of the key components of the UMLS, providing a unified, consistent compendium of many controlled vocabularies in the biomedical sciences. It helps facilitate interoperability between computer systems and services, such as those used in healthcare, by providing a comprehensive mapping of terms across different databases and coding standards.
Therefore, within the UMLS framework, one would find LOINC in the Metathesaurus component, which allows for the aggregation and cross-referencing of different medical terminologies and coding systems.