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Unified Medical Language System® (UMLS®)

National Library of Medicine (NLM) Medline Data Source Information

The National Library of Medicine MEDLINE® Data (NLM-MED) was developed and is maintained by the U.S. National Library of Medicine (NLM).

The MEDLINE database, produced by NLM, includes over 18 million journal article references related to the life sciences, with a focus on biomedicine.

NLM-MED provides frequency data for Medical Subject Headings (MeSH®).

NLM-MED contains information on the frequency of use of MeSH terms in MEDLINE from 1910 to the present. NLM-MED data is located in the MRSAT.RRF file in the Metathesaurus. There are no concepts included in this source.

For more information about MeSH in the Metathesaurus, see the MeSH source synopsis.

Metathesaurus Update Frequency
NLM-MED is an updated source in each Metathesaurus release.

Sites Consulted

  1. Fact sheet: MEDLINE® [Internet]. Bethesda (MD): National Library of Medicine (US); 2004 Nov 17 [updated 2010 Jun 2; cited 2010 Jul 30]. [about 6 screens]. Available from: