LOINC MCP Server

A Model Context Protocol server for querying LOINC (Logical Observation Identifiers Names and Codes) terminology through the LOINC Search API.

Available Tools

Tool	Description
search	Search LOINC codes by text query. Returns codes, names, and classifications.
get_code	Get full details for a LOINC code: parts, classification, units, panel members, and answer options.

Quick Start

Prerequisites

• Python 3.12+
• uv
• A LOINC account (free at loinc.org/join)

Install as a uv tool

git clone https://github.com/robsyc/loinc-mcp && cd loinc-mcp
uv tool install .

Then add to your .cursor/mcp.json or Claude Desktop config:

{
  "mcpServers": {
    "loinc-mcp": {
      "command": "loinc-mcp",
      "env": {
        "LOINC_USERNAME": "your-username",
        "LOINC_PASSWORD": "your-password"
      }
    }
  }
}

Run with uvx

{
  "mcpServers": {
    "LOINC": {
      "command": "uvx",
      "args": ["--from", "git+https://github.com/robsyc/loinc-mcp", "loinc-mcp"],
      "env": {
        "LOINC_USERNAME": "your-username",
        "LOINC_PASSWORD": "your-password"
      }
    }
  }
}

Usage Examples

"Search for LOINC codes related to glucose"

"Get the full details for LOINC code 2339-0"

"Look up the lipid panel 24331-1 and show me its members"

API Details

This server wraps the LOINC Search API:

• Base URL: https://loinc.regenstrief.org/searchapi/
• Auth: HTTP Basic Authentication (LOINC account credentials)
• Endpoints used: /loincs (search) and FHIR /Questionnaire/{code} (panels)
• Rate limiting: 10 requests/second (enforced client-side)

LOINC Class Types

Code	Type
1	Laboratory
2	Clinical
3	Claims attachments
4	Surveys

Panel Detection

When get_code is called for a panel (detected via the CLASS field), panel members are automatically fetched from the FHIR Questionnaire endpoint. For survey panels, answer options are included inline with each member.

Development

uv sync --group dev

# Lint
uv run ruff check src/ tests/

# Tests
uv run pytest tests/ -v

# MCP Inspector
LOINC_USERNAME=your-user LOINC_PASSWORD=your-pass uv run fastmcp dev inspector src/loinc_mcp/server.py:mcp

Acknowledgments

• LOINC for the terminology and API
• Regenstrief Institute for maintaining LOINC
• FastMCP for the MCP framework