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

# patient_identifier

An identifier for this patient, such as MRN or SSN (`Patient.identifier[]`).

**Primary Keys:**

* patient\_identifier\_id

**Foreign Keys:**

* patient\_id - links to the [patient](/medical-api/handling-data/schema-v100/patient/base) table

| Column                  | Data Type | Description                                                  |
| ----------------------- | --------- | ------------------------------------------------------------ |
| patient\_identifier\_id | varchar   | Unique identifier for the identifier row                     |
| patient\_id             | varchar   | Parent patient                                               |
| system                  | varchar   | Namespace/URI that defines the identifier value              |
| value                   | varchar   | The identifier value                                         |
| use                     | varchar   | Intended use of the identifier (e.g., official, usual, temp) |
| type\_text              | varchar   | Human-readable type description                              |
| period\_start           | datetime  | Start of the period when the identifier was valid            |
| period\_end             | datetime  | End of the period when the identifier was valid              |

**Related Tables:**

**Parent:**

* [patient](/medical-api/handling-data/schema-v100/patient/base)

**Child:**

* [patient\_identifier\_type\_coding](/medical-api/handling-data/schema-v100/patient/identifier_type_coding)