CodeSystem

The most comprehensive, multilingual clinical healthcare terminology in the world. It defines the clinical concepts used to document a patient's history, illness, and treatment.

• Domain: Clinical findings, procedures, body structures, organisms, substances, and events.
• Structure: Concepts are linked by polyhierarchical Is a relationships and defining attributes, enabling powerful semantic queries.
• Example: The concept Myocardial infarction has a unique SNOMED CT identifier (22298006) and is defined as a child of Ischemic heart disease with a Finding site of Myocardium.
• Key Role: The primary terminology for encoding clinical data in EHRs and is a required code system in the US Core Implementation Guide for problems and procedures.

A universal standard for identifying health measurements, observations, and documents. LOINC codes distinguish a test from its result, enabling the unambiguous exchange of lab and clinical data.

• Domain: Laboratory tests, clinical observations (vital signs, EKG), survey instruments, and clinical documents.
• Structure: A fully specified name is composed of six axes: Component, Property, Time, System, Scale, and Method.
• Example: The code 5792-7 represents a Glucose measurement with a Mass Concentration property on Serum/Plasma using a Quantitative scale.
• Key Role: Mandated by the USCDI standard for representing lab results and is essential for aggregating data across different hospital labs for public health reporting.

The official system for assigning codes to diagnoses and procedures in U.S. healthcare settings, primarily for billing and epidemiological tracking. It is a clinical modification of the WHO's ICD-10.

• Domain: Morbidity, mortality, and reasons for encounter. It classifies diseases, injuries, and external causes.
• Structure: Codes are alphanumeric and hierarchical, with categories, subcategories, and extension codes for laterality and episode of care.
• Example: E11.65 represents Type 2 diabetes mellitus with hyperglycemia. The E11 category is for Type 2 diabetes, and the .65 extension specifies the complication.
• Key Role: The foundational code system for payer claims processing and is used in FHIR's Claim and ExplanationOfBenefit resources to justify medical necessity.

A normalized naming system for generic and branded clinical drugs, produced by the U.S. National Library of Medicine. It links drug names from disparate pharmacy management and drug interaction systems into a single semantic network.

• Domain: Clinical drugs, branded drugs, dose forms, and their precise ingredients.
• Structure: Concepts are linked by relationships like has_tradename, has_ingredient, and has_dose_form to create a graph of drug knowledge.
• Example: The branded drug Lipitor and its generic equivalent Atorvastatin are linked to the same Ingredient concept, enabling a system to recognize them as the same medication.
• Key Role: The required standard for representing medications in the US Core MedicationRequest and MedicationStatement profiles, ensuring accurate medication reconciliation.

A medical code set maintained by the American Medical Association used to report medical, surgical, and diagnostic procedures and services to physicians, health insurance companies, and accreditation organizations.

• Domain: Physician services, surgical procedures, diagnostic tests, evaluation and management (E/M) visits, and immunizations.
• Structure: A five-character, hierarchical numeric code set divided into three categories: Category I (standard procedures), Category II (performance measurement), and Category III (emerging technologies).
• Example: 99213 is a common code for an established patient office visit requiring a medically appropriate history and examination with a low level of medical decision making.
• Key Role: The primary code system for billing professional services and is used in FHIR's Claim resource to define the service line items for reimbursement.

A unique, three-segment numeric identifier assigned to each medication product listed under the U.S. Federal Food, Drug, and Cosmetic Act. It serves as the universal product identifier for human drugs.

• Domain: The specific packaging of a finished drug product, including the manufacturer, product, and trade package size.
• Structure: A 10 or 11-digit code split into three segments: the Labeler (manufacturer), the Product (strength, dosage form), and the Package (size and type).
• Example: The NDC 0002-1201-05 identifies a specific bottle of 100 capsules of 20mg Prozac manufactured by Eli Lilly.
• Key Role: Essential for supply chain management, pharmacy dispensing, and billing for administered drugs. It is used in FHIR's Medication resource to identify the exact product administered or dispensed.