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Save lab results as FHIR LOINC Observations with optional Slack alerts

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Created by: Ciphernutz IT Services || ciphernutz
Ciphernutz IT Services

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Last update 3 days ago

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Quick overview

Receives lab results by webhook, validates them, maps each test to a LOINC-coded FHIR R4 Observation, and saves it with duplicate protection. Critical results can trigger a Slack alert without patient identifiers. Reference and panic ranges are configurable demo examples.

How it works

  1. Receives a POST request on the /lab-result webhook containing a JSON lab result payload.
  2. Loads template settings, validates required fields and formats (including ISO timestamps), and normalizes the test identifier.
  3. Maps the test to a supported LOINC code and expected unit, and enriches it with configurable reference and panic ranges.
  4. Checks for duplicates using an idempotency key and stops early with a duplicate response if the result was already processed.
  5. Builds a FHIR R4 Observation linked to Patient/{patient_id} and creates it on the target FHIR server using an If-None-Exist header to prevent duplicates.
  6. If the result is in the configured panic range and Slack alerts are enabled, posts a critical alert to Slack without patient identifiers, then returns the final status and Observation details to the webhook caller.

Setup

  1. Provide a reachable FHIR R4 base URL and ensure Patient/{patient_id} resources already exist on that server.
  2. If your FHIR server requires authentication, configure a Bearer token (or other auth method) on the HTTP request that posts the Observation.
  3. In the workflow settings node, review and replace the demo reference/panic ranges for each supported test with your lab-validated ranges.
  4. To enable critical alerts, create a Slack Incoming Webhook, paste its URL into the settings, and keep critical alerts turned on.
  5. Activate the workflow and send test requests to the /lab-result webhook URL from your lab system or integration source.

Requirements

  • n8n (self-hosted or Cloud)
  • A FHIR R4 server (the public HAPI test server works for demos)
  • Existing Patient resources on that server
  • Bearer token credential if your FHIR server requires authentication
  • Slack Incoming Webhook URL (optional, for critical alerts)
  • A lab system or source able to POST JSON to a webhook

Customization

  • Edit reference and panic ranges per test in the Settings node, with no code changes
  • Add a new test by adding its LOINC code, accepted unit and ranges in the "Map Test + Ranges" node
  • Replace the Slack alert node with Teams, email, SMS or another channel
  • Change the idempotency key to match your source system's unique result ID
  • Add unit conversion if your lab sends different units
  • Add a Patient lookup or create step if patients may not exist yet

Additional info

The reference and panic ranges are demo examples only and vary by laboratory, method and population; replace them before any clinical use. The optional patient_name field is accepted but never written to the Observation or sent to Slack. Treat your Slack webhook URL as a secret.

For more on integrating n8n with FHIR APIs, see Ciphernutz's guide: https://ciphernutz.com/blog/fhir-api-integration-using-n8n