curl -X GET "https://api.omophub.com/v1/domains?include_counts=true&vocabulary_ids=SNOMED" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json"

{
  "success": true,
  "data": [
    {
      "domain_id": "Condition",
      "domain_name": "Condition",
      "domain_concept_id": 19,
      "description": "A condition is a clinical or pathological state or episode that is observable, measurable, and is considered clinically significant for a patient's health status, clinical care or research purposes.",
      "concept_count": 125643,
      "vocabulary_counts": [
        {
          "vocabulary_id": "SNOMED",
          "vocabulary_name": "Systematized Nomenclature of Medicine Clinical Terms",
          "concept_count": 98765
        },
        {
          "vocabulary_id": "ICD10CM",
          "vocabulary_name": "International Classification of Diseases, Tenth Revision, Clinical Modification",
          "concept_count": 26878
        }
      ],
      "examples": [
        "Type 2 diabetes mellitus",
        "Hypertensive disease",
        "Asthma",
        "Pneumonia"
      ]
    },
    {
      "domain_id": "Procedure",
      "domain_name": "Procedure",
      "domain_concept_id": 10,
      "description": "A procedure is an activity directed at or performed on a patient with the intention of diagnosing, treating, or preventing a condition.",
      "concept_count": 87321,
      "vocabulary_counts": [
        {
          "vocabulary_id": "SNOMED",
          "vocabulary_name": "Systematized Nomenclature of Medicine Clinical Terms",
          "concept_count": 65432
        }
      ],
      "examples": [
        "Coronary artery bypass graft",
        "Appendectomy", 
        "Chest X-ray",
        "Colonoscopy"
      ]
    },
    {
      "domain_id": "Drug",
      "domain_name": "Drug",
      "domain_concept_id": 13,
      "description": "A drug is a biochemical substance formulated to provide a therapeutic effect when administered to a patient.",
      "concept_count": 45678,
      "vocabulary_counts": [
        {
          "vocabulary_id": "RXNORM",
          "vocabulary_name": "RxNorm",
          "concept_count": 32456
        },
        {
          "vocabulary_id": "NDC",
          "vocabulary_name": "National Drug Code",
          "concept_count": 13222
        }
      ],
      "examples": [
        "Metformin",
        "Insulin",
        "Aspirin",
        "Lisinopril"
      ]
    },
    {
      "domain_id": "Measurement",
      "domain_name": "Measurement",
      "domain_concept_id": 21,
      "description": "A measurement is a standardized result of testing or examination of an entity.",
      "concept_count": 34567,
      "vocabulary_counts": [
        {
          "vocabulary_id": "LOINC",
          "vocabulary_name": "Logical Observation Identifiers Names and Codes",
          "concept_count": 28934
        },
        {
          "vocabulary_id": "SNOMED",
          "vocabulary_name": "Systematized Nomenclature of Medicine Clinical Terms", 
          "concept_count": 5633
        }
      ],
      "examples": [
        "Blood glucose measurement",
        "Hemoglobin level",
        "Blood pressure measurement",
        "Body weight"
      ]
    }
  ],
  "meta": {
    "request_id": "req_domains_123",
    "timestamp": "2024-01-15T10:30:00Z",
    "total_domains": 25,
    "pagination": {
      "page": 1,
      "page_size": 50,
      "total_items": 25,
      "total_pages": 1,
      "has_next": false,
      "has_previous": false
    },
    "vocab_release": "2025.2"
  }
}