Quantities: Finding laboratory values
There are a few options to search Observation resources for lab tests. You can search for all lab tests or specific lab tests for all patients or a specific patient.
Request: Search query for all lab tests for a patient
The following search query uses the laboratory category to find all lab tests for a given patient.

Request: Search for a specific lab test for all patients
To find a specific lab test, you can use the LOINC code for that test and the code search parameter. For example, the following search query finds all Potassium tests (LOINC code 6298-4) across all patients.

Request: Search for a value and quantity
You can also add a value-quantity search parameter to find, for example, potassium tests with a specific value. The following example searches for any potassium tests with a value below 4.0 mmol/L.

Parent topic: FHIR Search operations