LOINC Hierarchy

This tool showcases the LOINC hierarchy that systematically categorize laboratory observations in healthcare systems for effective communication in EHR.

1. LOINC Code

LOINC (Logical Observation Identifiers Names and Codes) is a standardized coding system used globally to report laboratory and other clinical observations. The LOINC database contains over 71,000 terms, each described by a six-part structure that includes component, property, time aspect, system, scale, and method.

2. LOINC Part Code:

The six parts categorized in LOINC system are detailed below:

• Component indicates what is measured, evaluated, or observed.
• Property indicates characteristics of what is measured.
• Time aspect indicates interval of time over which the observation or measurement was made.
• System indicates context or specimen type within which the observation was made, e.g. blood or urine.
• Scale indicates the scale of measure.
• Method indicates the procedure used to make the measurement or observation.

Related: Major Parts of a LOINC term

The LOINC parts have codes beginning with LP. For example, LP14559-6 stands for Bacteria.

3. LOINC component

As discussed before, the LOINC component indicates the biological or clinical entities that are measured, evaluated or observed.

Quick Start Guide

This app has two top-level pages in the navigation bar:

• Documentation: this guide.
• Main page: the interactive explorer.

On the Main page, use either AI Chat or Manual Search (left sidebar) to populate the table, then select a row to explore the hierarchy.

1. Find LOINC rows

   • AI Chat (recommended): type a term like crp or neutro.
     • Export example: download csv for loinc 1988-5.
     • If you want SQL, explicitly ask for SQL.
   • Manual Search: choose Dataset / Search Method / Cutoff, then type in the Search box.

2. Select a LOINC code

   • Click a row in LOINC Info to set the active LOINC code.

3. Explore the hierarchy

   • TreeList (left) shows an expandable list.
   • TreeView (right) shows a graphical view.

Table

LOINC Info (top)

• Click a row to select the active LOINC code.
• Use Table Options (the sidebar within the table card) to show/hide additional columns.

Common columns:

• LOINC: code of the LOINC term
• LOINC Description: the term’s official description in LOINC system (usually a combination of abbreviated medical terminologies)
• Component, Property, Time, System, Scale, Method: the six parts that are involved in the LOINC term (see detailed explanation of each part above)
• Long common name: detailed description of the LOINC term in full terminologies

Visualizations

TreeList

• The root of the tree shows the main component and its corresponding LOINC part codes. The child branches show LOINC parts with code and description that fall under the component. The end nodes show LOINC code with their description.
• The selected LOINC term from the top table would be highlighted in blue

TreeView

• TreeView directly visualize the TreeList structure displayed on the left
• The selected LOINC term from the top table or TreeList would be highlighted in red.

Use Cases

Laboratory tests can be reported via a range of coding systems, such as local codes and standardized LOINC codes, to represent distinct tests and methodologies. This adds a lot of complexity when leveraging electronic health records (EHRs) in clinical research. The LOINC Hierarchy tool mitigates this complexity by structuring LOINC codes within a hierarchical framework, which simplifies the process of identifying and comparing tests and facilitates the harmonization of data across different healthcare institutions.