Code Standards

A coding and terminology framework is essential to standardizing laboratory reporting and enabling interoperability of information exchange across Electronic Health Record (EHR) platforms.


Logical Observation Identifiers Names and CodesExternal Web Site Policy (LOINC®) is a terminology standard for identifying laboratory tests and other measurements. It specifies universal codes, names, and other attributes for laboratory results as well as clinical reports, physical exam findings, survey instruments and other observations. It was developed to enable the exchange and pooling of results from diverse sources in order to enhance clinical care, outcomes management and research. The LOINC terminology is available free of charge and was developed by the LOINC Committee and Regenstrief Institute, Inc., a non-profit medical research organization associated with Indiana University. The database is maintained by Regenstrief and updated versions are released twice a year. The LOINC web search tool is available at http://search.loinc.org/External Web Site Policy, or you can download the database and a free browser program, the Regenstrief LOINC Mapping Assistant (RELMA®), from http://loinc.org/downloadsExternal Web Site Policy. The LOINC and RELMA Terms of Use are available at http://loinc.org/terms-of-useExternal Web Site Policy.


Systematized Nomenclature of Medicine — Clinical Terms (SNOMED CT®) is a comprehensive, multilingual clinical health care terminology. It is designed for use in electronic health record systems and aims to facilitate communication and interoperability in electronic health data exchange. Originally created by the College of American Pathologists (CAP) in cooperation with the National Health Service in England, SNOMED CT is now owned, maintained, and distributed by the International Health Terminology Standards Development Organisation (IHTSDO), an international not-for-profit association in Denmark, with contract assistance from the CAP. It is available free of charge in IHTSDO member countries, including the U.S., in low-income countries as defined by the World Bank, and for qualified research projects in any country. The National Library of Medicine (NLM) is the U.S. representative to the IHTSDO. Information about obtaining SNOMED CT is available through NLM's Unified Medical Language System (UMLS®) Metathesaurus at http://www.nlm.nih.gov/research/umls/licensedcontent/snomedctfiles.html. A free UMLS license (which includes the IHTSDO Affiliate license) is required and can be obtained at the same site.

The Newborn Screening Coding and Terminology Guide uses some codes from the US Extension to SNOMED CT.


International Classification of Diseases, Ninth Revision, Clinical Modification, vols. 1-2 (ICD-9-CM), is based on the World Health Organization's (WHO) Ninth Revision, International Classification of Diseases (ICD-9). The codes in the Clinical Modification are more precise than those in ICD-9 in terms of clinical detail, and are intended to serve as a useful tool for classifying morbidity data for indexing medical records, medical care review, and ambulatory and other medical care programs, as well as for basic health statistics. However, despite ICD-9-CM's precision compared to ICD-9, in some cases, one ICD-9-CM code will still be used for more than one condition. For example, several amino acid disorders, including argininosuccinic aciduria, citrullinemia and Ornithine transcarbamylase deficiency, are represented by the code 270.6.

ICD-9-CM is the official standard for assigning codes to diagnoses associated with hospital utilization and public health reporting in the U.S., and is required for use in administrative transactions subject to the Health Insurance Portability and Accountability Act of 1996 (HIPAA). The Centers for Medicare & Medicaid Services and the National Center for Health Statistics (NCHS), part of the Centers for Disease Control and Prevention, are the U.S. governmental agencies responsible for overseeing all changes and modifications to the ICD-9-CM. There are no constraints on the use of ICD-9-CM codes. ICD-9-CM codes and terminology can be obtained from the NCHS at http://www.cdc.gov/nchs/icd/icd9cm.htm and from the UMLS Metathesaurus at http://www.nlm.nih.gov/research/umls/licensedcontent/downloads.html. A free UMLS Metathesaurus license is required to use Metathesaurus content and can be obtained at the same site.


International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) is the United States' clinical modification of the WHO's Tenth Revision, International Classification of Diseases (ICD-10). The ICD-10 Clinical Modification has the same purpose as the ICD-9-CM: to create codes that are more granular and therefore give a more accurate clinical description. However, despite ICD-10-CM's precision compared to ICD-10, in some cases, one ICD-10-CM code will still be used for more than one condition. For example, Long chain acyl CoA dehydrogenase deficiency and very long chain acyl CoA dehydrogenase deficiency both have the code E71.310.

ICD-10-CM is scheduled to replace ICD-9-CM, vols. 1 and 2, as a HIPAA standard. The Centers for Medicare & Medicaid Services (https://www.cms.gov/Medicare/Coding/ICD10/) have the latest information on the ICD-10-CM implementation schedule. The NCHS is the U.S. governmental agency responsible for overseeing all changes and modifications to the ICD-10-CM. There are no constraints on the use of ICD-10-CM codes, which are freely available at http://www.cdc.gov/nchs/icd/icd10cm.htm and in the UMLS at http://www.nlm.nih.gov/research/umls/licensedcontent/downloads.html.

Enzyme Codes

"Enzyme Nomenclature" is a list of enzymes with their recommended names, Enzyme Commission (EC) codes, and classifications. It was created and is maintained by the Nomenclature Committee of the International Union of Biochemistry and Molecular Biology (NC-IUBMB) in consultation with the Joint Commission on Biochemical Nomenclature (JCBN). The JCBN is a collaborative effort of the International Union of Pure and Applied Chemistry (IUPAC) and the IUBMB. The entries are protected by copyright assigned to the IUBMB. The enzyme codes are freely available for use and can be found at http://www.sbcs.qmul.ac.uk/iubmb/enzyme/External Web Site Policy.


Online Mendelian Inheritance in ManExternal Web Site Policy® (OMIM®) is a comprehensive, authoritative, and timely compendium of human genes and genetic phenotypes. It was originally authored and edited by Dr. Victor McKusick, a pioneer of medical genetics and the author of "Mendelian Inheritance in Man," and is now maintained by Johns Hopkins University. The full-text, referenced overviews in OMIM contain information on over 12,000 genes and on all known Mendelian disorders. OMIM focuses on the relationship between genotype and phenotype. It is updated daily, and the entries contain links to many other genetics resources. OMIM and Online Mendelian Inheritance in Man are registered trademarks of the Johns Hopkins University. Copyright © 1966-2011 Johns Hopkins University.


Universal Protein Resource (UniProt) is a comprehensive, international resource for information about protein sequence and function. The UniProt accession number is a unique number assigned to an individual protein. The UniProt database includes enzymes as well as other proteins such as hemoglobin subunits and immunoglobulin chains. UniProt is the result of collaboration between the European Bioinformatics Institute, the Swiss Institute of Bioinformatics, and the Protein Information Resource, which is maintained by the Georgetown University Medical Center and the University of Delaware. The database is freely available at http://www.uniprot.orgExternal Web Site Policy.