> ## Documentation Index
> Fetch the complete documentation index at: https://docs.omophub.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Get Vocabulary Concept Classes

> Retrieve all concept classes within a specific OMOP vocabulary - Clinical Finding for SNOMED, Ingredient for RxNorm, and each vocabulary's class set.

## Overview

This endpoint returns all OMOP concept classes, providing insights into the classification structure of medical concepts.

## Query Parameters

<ParamField query="vocab_release" type="string">
  Specific vocabulary release version (e.g., "2025.1")
</ParamField>

## Response

<ResponseField name="success" type="boolean" required>
  Indicates whether the request was successful
</ResponseField>

<ResponseField name="data" type="array" required>
  Array of concept classes

  <Expandable title="concept class object">
    <ResponseField name="concept_class_id" type="string">
      Unique identifier for the concept class
    </ResponseField>

    <ResponseField name="concept_class_name" type="string">
      Human-readable name of the concept class
    </ResponseField>

    <ResponseField name="concept_class_concept_id" type="integer">
      The concept ID representing this concept class
    </ResponseField>
  </Expandable>
</ResponseField>

<ResponseField name="meta" type="object" required>
  Response metadata

  <Expandable title="meta">
    <ResponseField name="request_id" type="string">
      Unique identifier for request tracing
    </ResponseField>

    <ResponseField name="timestamp" type="string">
      ISO 8601 timestamp
    </ResponseField>

    <ResponseField name="vocab_release" type="string">
      Vocabulary release version used
    </ResponseField>
  </Expandable>
</ResponseField>

<RequestExample>
  ```bash cURL theme={null}
  curl -X GET "https://api.omophub.com/v1/vocabularies/concept-classes" \
    -H "Authorization: Bearer YOUR_API_KEY"
  ```

  ```python Python theme={null}
  import requests

  response = requests.get(
      "https://api.omophub.com/v1/vocabularies/concept-classes",
      headers={"Authorization": "Bearer YOUR_API_KEY"}
  )
  data = response.json()
  ```
</RequestExample>

<ResponseExample>
  ```json theme={null}
  {
    "success": true,
    "data": [
      {
        "concept_class_id": "Clinical Finding",
        "concept_class_name": "Clinical Finding",
        "concept_class_concept_id": 404684003
      },
      {
        "concept_class_id": "Procedure",
        "concept_class_name": "Procedure",
        "concept_class_concept_id": 71388002
      },
      {
        "concept_class_id": "Substance",
        "concept_class_name": "Substance",
        "concept_class_concept_id": 105590001
      }
    ],
    "meta": {
      "request_id": "req_abc123",
      "timestamp": "2024-12-22T10:30:00Z",
      "vocab_release": "2025.1"
    }
  }
  ```
</ResponseExample>

## Notes

* Returns all concept classes from the vocabulary database
* Results are ordered alphabetically by concept class name
* The `concept_class_concept_id` field contains the concept ID that represents this concept class