Terminology Standards

These standards address a fundamental requirement for effective communication – the ability to represent concepts in an unambiguous manner between a sender and receiver of information. Most communication between health information systems relies on structured vocabularies, terminologies, code sets and classification systems to represent health concepts.

Why Do We Need Standard Terminology in Health Informatics?

Standard terminology provides a foundation for interoperability by improving the effectiveness of information exchange. Using standard terminology should be a simple and logical step in health IT. However, with the complexities of many diagnoses systems, clinical narrative transferred via PDF format, various coding systems, and the cost of digitizing volumes of reference material/dictionaries, it isn’t as easy as you would think.

Structured terms provide a means for organizing information and serve to define the semantics of information using consistent and computable mechanisms. Therefore, health information specialists need the tools to focus on delivering terminology through a common delivery system to the software vendors and institutions in a consistent, high quality and verifiable fashion. Vendors and institutions need to be able to write applications that access terminology content, be it SNOMED, immunization data, demographics, LOINC, or a coding system local to the institution in exactly the same way.

See below for some of the common terminology standards used in health information and technology.


Logical Observation Identifiers Names and Codes (LOINC®) is a universal code system for identifying health measurements, observations, and documents. These codes represent the “question” for a test or measurement. LOINC codes can be grouped into Laboratory and Clinical tests, measurements and observations. Visit LOINC’s database to explore these data standards.


The Unified Code for Units of Measure (UCUM) is a code system intended to include all units of measures used in international science, engineering and business to facilitate unambiguous electronic communication of quantities together with their units.


Systematized Nomenclature of Medicine--Clinical Terms (SNOMED CT) is a comprehensive clinical health terminology product, owned and distributed by SNOMED International. It enables the consistent, processable representation of clinical content in electronic health records. These codes often represent the “answer” for a test or measurement to the LOINC “question” code. Explore these standards.


RxNorm provides normalized names for clinical drugs and links its names to many of the drug vocabularies commonly used in pharmacy management and drug interaction software. By providing links between these vocabularies, RxNorm can mediate messages between systems not using the same software and vocabulary. RxNorm now includes the National Drug File - Reference Terminology (NDF-RT) from the Veterans Health Administration. NDF-RT is a terminology used to code clinical drug properties, including mechanism of action, physiologic effect, and therapeutic category. Explore the RxNorm standards database.


RadLex is a unified language of radiology terms for standardized indexing and retrieval of radiology information resources. It unifies and supplements other lexicons and standards, such as SNOMED-CT and DICOM. It is managed by the Radiological Society of North America.


MEDCIN is a medical terminology, maintained by Medicomp Systems, that encompasses symptoms, history, physical examination, tests, diagnoses and therapies.


ICD-10 is the 10th revision of the International Statistical Classification of Diseases and Related Health Problems(ICD), a medical classification list by the World Health Organization (WHO). It contains codes for diseases, signs and symptoms, abnormal findings, complaints, social circumstances, and external causes of injury or diseases.


Current Procedural Terminology (CPT®) is a code set, maintained by the American Medical Association (AMA) used to bill outpatient and office procedures.


The Healthcare Common Procedure Coding System (HCPCS) is a set of healthcare procedure codes based on CPT that is leveraged for Medicare reimbursement.


The Centers for Disease Control and Prevention (CDC) provide a number of code sets for vaccines (Vaccines Administered (CVX)) and manufacturers (Manufacturers of Vaccines (MVX)). These codes can be used in immunization messages. Explore the CVX database.


The National Drug Code (NDC) is maintained by the Food and Drug Administration (FDA) and provides a list of all drugs manufactured, prepared, propagated, compounded or processed for commercial distribution. Search the NDC database.