Commonly Used Terminologies | Medplum

Overview of Common Code Systems

The following table shows the most commonly used code system for each clinical application area:

Clinical Application	Primary Code System	CodeSystem URL	Description	Full System Valueset
Clinical Findings	LOINC	`http://loinc.org`	Laboratory tests, vital signs, clinical observations	`http://loinc.org/vs`
Medications	RXNorm	`http://www.nlm.nih.gov/research/umls/rxnorm`	Normalized medication names	`http://www.nlm.nih.gov/research/umls/rxnorm/vs`
Procedures	CPT	`http://www.ama-assn.org/go/cpt`	Current Procedural Terminology	`http://www.ama-assn.org/go/cpt/vs`
Diagnoses	ICD-10-CM	`http://hl7.org/fhir/sid/icd-10-cm`	International Classification of Diseases, Clinical Modification	`http://hl7.org/fhir/sid/icd-10-cm/vs`
Vaccines	CVX	`http://hl7.org/fhir/sid/cvx`	Vaccine Administered	`http://hl7.org/fhir/sid/cvx/vs`
Allergies (food + environmental)	SNOMED CT	`http://snomed.info/sct`	Substance and clinical concepts	`http://snomed.info/sct/vs`

Use-case Specific ValueSets

Each clinical area has predefined sets of codes that cover the most common scenarios you'll encounter. While each clinical area has a primary code system, healthcare applications often need to support multiple coding systems for different use cases.

Clinical Findings and Laboratory Tests

Valueset Name	Description	Valueset URL	Example Values	Code Systems
Vital Signs Type	Codes for types of vital sign measurements and clinical observations	`http://hl7.org/fhir/us/core/ValueSet/us-core-vital-signs`	`[8302-2] Body height`, `[8867-4] Heart rate`	LOINC
Smoking Status	Codes for patient smoking status and tobacco use	`http://cts.nlm.nih.gov/fhir/ValueSet/2.16.840.1.113883.11.20.9.38`	`[8517006] Ex-smoker`	SNOMED CT
Pregnancy Status	Codes for pregnancy status and related observations	`http://hl7.org/fhir/us/core/ValueSet/us-core-pregnancy-status`	`[77386006] Pregnancy`	SNOMED CT
SDOH Assessment	Social determinants of health assessment codes	`http://hl7.org/fhir/us/core/ValueSet/us-core-common-sdoh-assessments`	`[71802-3] Housing status`	LOINC
Sexual Orientation	Codes for sexual orientation and gender identity	`http://hl7.org/fhir/us/core/ValueSet/us-core-sexual-orientation`	`[20430005] Heterosexual`	SNOMED CT

Allergies and Adverse Reactions

Allergy coding uses SNOMED CT for substance identification and RXNorm for medication allergies, following US Core 5.0.1 specifications.

Code System	System URL	Description	Use Cases
SNOMED CT	`http://snomed.info/sct`	Substance and clinical concepts	Food allergies, environmental allergies, clinical findings
RXNorm	`http://www.nlm.nih.gov/research/umls/rxnorm`	Medication substances	Drug allergies, medication intolerances

Common ValueSets

Valueset Name	Description	Valueset URL	Example Values	Code Systems
US Core Allergy Substance	Common substances for allergy and intolerance documentation including refutations	`http://cts.nlm.nih.gov/fhir/ValueSet/2.16.840.1.113762.1.4.1186.8`	`[7980] Penicillin G`	SNOMED CT, RXNorm

Medications

For detailed information about medication coding systems including RxNorm and NDC, see Medication Code Systems.

Medical Procedures

Procedure coding varies by setting and purpose, with CPT being primary for billing.

Code System	System URL	Description	Use Cases
CPT	`http://www.ama-assn.org/go/cpt`	Current Procedural Terminology	Billing, procedure documentation
HCPCS	`https://www.cms.gov/Medicare/Coding/HCPCSReleaseCodeSets`	Healthcare Common Procedure Coding System	Medicare/Medicaid billing, Value-based care, DME
SNOMED CT	`http://snomed.info/sct`	Clinical procedure concepts	Clinical documentation, procedure notes
ICD-10-PCS	`http://www.cms.gov/Medicare/Coding/ICD10`	ICD-10 Procedure Coding System	Hospital inpatient billing

Diagnoses and Conditions

Diagnosis coding primarily uses ICD-10-CM for standardized disease classification, with SNOMED CT providing more granular clinical concepts preferred in international settings.

Code System	System URL	Description	Use Cases
ICD-10-CM	`http://hl7.org/fhir/sid/icd-10-cm`	International Classification of Diseases, Clinical Modification	Primary diagnoses, billing, epidemiology
SNOMED CT	`http://snomed.info/sct`	Clinical findings and disorders	Clinical documentation, problem lists

Vaccines and Immunizations

Vaccine coding uses CVX codes for vaccine types and CPT codes for administration procedures.

Code System	System URL	Description	Use Cases
CVX	`http://hl7.org/fhir/sid/cvx`	Vaccine Administered	Immunization records, vaccine administration
CPT	`http://www.ama-assn.org/go/cpt`	Vaccine administration procedures	Billing for vaccine administration