C3844221

UMLS CUI C3844221 is "A proper value is applicable but not known. This event occurred, but the date is unknown (e.g., chemotherapy administered but date is unknown).".

A proper value is applicable but not known. This event occurred, but the date is unknown (e.g., chemotherapy administered but date is unknown). (CUI C3844221) groups: 1 LOINC code.

The Unified Medical Language System is the NLM's meta-terminology that unifies SNOMED CT, ICD-10, ICD-11, RxNorm, LOINC, MeSH, and around 200 other source vocabularies under a single concept identifier (CUI). One UMLS CUI can group dozens of synonymous codes from different terminologies.

A CUI is a stable identifier (like C0011860) that points at a single clinical idea regardless of how that idea is encoded in any specific vocabulary. CUIs are the most reliable way to bridge between terminologies when you need to compare or merge data from multiple sources.

Every UMLS concept page lists the codes it groups together. That gives you a free crosswalk: a SNOMED concept and an ICD-10 code that share a CUI describe the same clinical idea. Our cross_references API returns these groupings inline.

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