FHIR R4 Observation example: laboratory result

A single laboratory result is an Observation in the laboratory category. The LOINC code names the analyte and specimen; the reference range and interpretation travel with the value, so the result can be read outside the lab's PDF.

The Observation in JSON

{
  "resourceType": "Observation",
  "id": "glucose",
  "status": "final",
  "category": [
    {
      "coding": [
        {
          "system": "http://terminology.hl7.org/CodeSystem/observation-category",
          "code": "laboratory",
          "display": "Laboratory"
        }
      ]
    }
  ],
  "code": {
    "coding": [
      {
        "system": "http://loinc.org",
        "code": "2345-7",
        "display": "Glucose [Mass/volume] in Serum or Plasma"
      }
    ],
    "text": "Glucose"
  },
  "subject": {
    "reference": "Patient/example",
    "display": "Jane Doe"
  },
  "effectiveDateTime": "2026-10-02T07:45:00-05:00",
  "issued": "2026-10-02T13:10:00-05:00",
  "performer": [
    {
      "reference": "Organization/lab",
      "display": "Springfield Clinical Laboratory"
    }
  ],
  "valueQuantity": {
    "value": 126,
    "unit": "mg/dL",
    "system": "http://unitsofmeasure.org",
    "code": "mg/dL"
  },
  "interpretation": [
    {
      "coding": [
        {
          "system": "http://terminology.hl7.org/CodeSystem/v3-ObservationInterpretation",
          "code": "H",
          "display": "High"
        }
      ]
    }
  ],
  "referenceRange": [
    {
      "low": {
        "value": 70,
        "unit": "mg/dL",
        "system": "http://unitsofmeasure.org",
        "code": "mg/dL"
      },
      "high": {
        "value": 99,
        "unit": "mg/dL",
        "system": "http://unitsofmeasure.org",
        "code": "mg/dL"
      }
    }
  ]
}

Validator result with the eu-lab profile: raw JSON · open the validator

• informationNo errors: this Observation matches the FHIR R4 structure checked here.

The elements that matter

The validator below this page runs this example with the optional eu-lab rules (category, LOINC code, UCUM unit, reference range). Choose the profile in the validator to run the same check on your own results.

The full definition is in the FHIR R4 Observation specification.

Common mistakes and the errors they cause

Status outside the value set

Observation.status has a required binding; done is not in it.

• errorObservation.statusObservation.status 'done' is not in the required value set (amended, cancelled, corrected, entered-in-error, final, preliminary, registered, unknown).
• errorObservation.statusObservation.status must be final, amended, corrected or preliminary.

Value and unit in one string

valueQuantity.value is a decimal; the unit goes in unit and code.

• errorObservation.valueQuantity.valueNot a FHIR decimal (a JSON number such as 7.2).

Two value[x] elements

An Observation has one value; use components for several.

• errorObservationOnly one of these elements may be present: valueBoolean, valueCodeableConcept, valueDateTime, valueInteger, valuePeriod, valueQuantity, valueRange, valueRatio, valueSampledData, valueString, valueTime.

More examples

• Patient resource example
• Observation example: blood pressure
• DiagnosticReport example: lab panel
• Condition resource example
• MedicationStatement example
• AllergyIntolerance example
• Immunization resource example
• Encounter resource example

Related guides

• How to import laboratory results into a FHIR recordTutorial: import a lab report as CSV and as HL7 v2 ORU^R01 into FHIR R4 Observations with LOINC codes and reference ranges, handle unmapped markers and resent reports, and trace each result to its laboratory.
• How to normalize medical dataTutorial: turn medical data from many sources into one comparable form — LOINC and ATC lookup, UCUM units, ISO dates, reference ranges, no duplicates on retry, and validation against the European lab profile.