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In order to standardize medical data coming from a variety of sources, Metriport makes use of the HL7 FHIR R4 data standard.

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What is FHIR?

FHIR (pronounced fire🔥) is a data standard that represents various healhcare concepts, and is used to facilitate interoperability between healthcare IT systems. You can think of it like this: every API has a spec, along with some data models, so that different systems can communicate with the API - FHIR is the modern spec that allows healthcare IT systems to communicate with each other.

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Resources & Data Types

After you initiate a new document query for a given patient, Metriport will automatically convert any newly found C-CDA documents from XML to the corresponding FHIR Resources in JSON. A FHIR Resource is a representation of some concept related to healthcare. Some examples include:
  • Encounter: an interaction between a patient and healthcare provider(s).
  • MedicationRequest: an order or request for both supply of the medication and the instructions for administration of the medication to a patient.
  • Observation: measurements about a patient - ie weight, height, blood pressure, etc.
In JSON, an Observation Resource would look like this, for example: 
{
  "resourceType": "Observation",
  "meta": {
    "lastUpdated": "2025-10-22T14:56:59.704Z",
    "source": "01964571-db3c-7953-9987-fe7b62cc278c/01964571-db3c-7953-9987-fe7cb3d109e4/01964571-db3c-7953-9987-fe7b62cc278c_01964571-db3c-7953-9987-fe7cb3d109e4_01964571-db3c-7953-9987-fe7d7dcb476d.xml"
  },
  "id": "00000000-0000-0000-0000-000000000000",
  "category": [
    {
      "coding": [
        {
          "system": "http://terminology.hl7.org/CodeSystem/observation-category",
          "code": "vital-signs",
          "display": "Vital Signs"
        }
      ],
      "text": "Vital Signs"
    }
  ],
  "status": "final",
  "code": {
    "text": "Body mass index (BMI) [Ratio]",
    "coding": [
      {
        "code": "39156-5",
        "display": "Body mass index (BMI) [Ratio]",
        "system": "http://loinc.org"
      }
    ]
  },
  "effectiveDateTime": "2024-01-18T05:00:00.000Z",
  "valueQuantity": {
    "value": 26.4,
    "unit": "kg/m2",
    "system": "http://unitsofmeasure.org"
  },
  "subject": {
    "reference": "Patient/00000000-0000-0000-0000-000000000000"
  },
  "performer": [
    {
      "reference": "Practitioner/11111111-1111-1111-1111-111111111111"
    },
    {
      "reference": "Organization/22222222-2222-2222-2222-222222222222"
    }
  ],
  "extension": [
    {
      "url": "https://public.metriport.com/fhir/StructureDefinition/doc-id-extension.json",
      "valueString": "01964571-db3c-7953-9987-fe7b62cc278c/01964571-db3c-7953-9987-fe7cb3d109e4/01964571-db3c-7953-9987-fe7b62cc278c_01964571-db3c-7953-9987-fe7cb3d109e4_01964571-db3c-7953-9987-fe7d7dcb476d.xml"
    }
  ]
}
You’re able to query for a Patient’s FHIR Resources using the Consolidated Data Query Endpoint. Additionally, to meet data contribution requirements, you’re able to provide new data about a Patient using the Add Patient Data endpoint.
You can see the HL7 FHIR Resource Index for an overview of various FHIR Resources by category, as well as our Resource List.
FHIR Resources each have their own specification for properties that may be included in the Resource, and they may contain one or more of the defined Data Types.

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Meta

The meta.source property in any FHIR resource points to the C-CDA source document from which the resource was derived. You can use this value with the Get Document URL endpoint to download the original C-CDA document.

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Extensions

The FHIR specification is fairly flexible, and it allows for additions on every base resource through “Extensions”. This allows healthcare IT systems to provide more information to the resource, that may be relevant to their specific implementation. Extensions can be available under the extension property on any FHIR Resource, and also have their own specification for data they can contain. For example, Metriport introduces a Condition Chronicity Extension inside FHIR Condition resources to specify whether the underlying medical condition is chronic.

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Coding Systems

Clinical concepts are best described by using specific codes from standardized coding systems, such as ICD-10-CM, SNOMED, and others. These can be found in the coding arrays of many FHIR Resources. Metriport maximizes the use of codes provided in the source clinical documents, while also saturating the data with systems, such as CCSR.