Not ICD, not CPT: The terminologies that power laboratory data behind the scenes

Coding professionals are deeply familiar with ICD-10-CM/PCS and CPT^® codes. These classification systems play a critical role in reimbursement, reporting and quality initiatives. But when it comes to laboratory data, another set of standards quietly does the heavy lifting behind the scenes.

In my work with laboratory terminologies, I often see confusion about the role of CPT codes versus clinical terminologies such as LOINC and SNOMED CT. While CPT accurately captures the work involved in performing a test, it was never designed to communicate the full clinical meaning of a laboratory observation. That's where LOINC and SNOMED CT come in.

As laboratory results move between electronic health records (EHRs), health information exchanges, registries, public health agencies and research platforms, systems need a standardized way to understand exactly what was tested and how results should be interpreted. LOINC provides the framework for identifying laboratory tests and observations, while SNOMED CT helps standardize many non-numeric result values, organisms and specimen descriptions. 

Consider a simple example. A CPT code may accurately describe a laboratory service for billing purposes, but it often lacks the specificity needed to distinguish one clinical test from another. LOINC, on the other hand, captures critical details such as the analyte, specimen type, timing and methodology, enabling systems to exchange and interpret data consistently. 

SNOMED CT plays an equally important role. Whether a result is reported as positive, negative or identifies a specific microorganism, SNOMED CT provides a standardized way for computer systems to recognize and reuse that information across organizations. This consistency supports interoperability, analytics, public health reporting and clinical decision-making. 

For organizations undertaking terminology mapping projects, success depends on more than selecting the right code. It requires collaboration among laboratory, coding and IT teams, along with careful review of local test catalogs, result values and workflows. While SNOMED CT mapping may be relatively straightforward in some areas, LOINC mapping often requires deeper laboratory expertise to ensure accurate representation of clinical meaning. 

The value of this work extends far beyond compliance. Effective terminology mapping helps ensure that laboratory data remains understandable, reusable and interoperable wherever it travels.

To learn more about this topic, including practical examples of LOINC and SNOMED CT implementation and guidance for terminology mapping projects, read Pam’s full article on JustCoding.

Pam Banning is a senior healthcare data analyst for Solventum and currently the co-chair of the laboratory LOINC committee.