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

# FHIR Implementation Guide

> Input and output FHIR shapes MedListIQ understands and produces.

<Note>
  A formal IG is in progress. This page documents the current shapes in prose;
  the IG artifacts (StructureDefinitions, examples, CapabilityStatement) will
  be published here when ready.
</Note>

## Input profiles

MedListIQ accepts standard **FHIR R4** medication resources. Any mix of the following in a single request:

* **`MedicationRequest`** — orders and prescriptions. Status, intent, dosage instructions, reason codes.
* **`MedicationDispense`** — pharmacy fills. Proves the patient actually received the drug.
* **`MedicationStatement`** — patient-reported or clinician-reported medication history.
* **`MedicationAdministration`** — administration events (inpatient / infusion settings).
* **`Medication`** — referenced via `medicationReference` from the above. Resolved during processing.

Pass them as a flat `resources` array, a FHIR `Bundle`, or both. No `Patient` or `subject` references required — requests are single-patient-scoped by the API key's calling context.

## Output profiles

Pick a response shape via the `format` request parameter:

* **`inferred_list`** (default) — our proprietary JSON: `{ medications, provenance?, meta }`. Purpose-built for dashboards, UIs, and CDS engines.
* **`fhir_bundle`** — FHIR R4 `Bundle` of `MedicationRequest` resources. At `verbosity=full`, companion `Provenance` resources are included in the same Bundle, each targeting a MedicationRequest and carrying our inference evidence + enrichments as extensions.
* **`fhir_array`** — flat list of FHIR resources (no Bundle wrapper). At `verbosity=full`, the array contains `MedicationRequest` resources followed by `Provenance` resources, identified by their `resourceType` field. Pipeline-friendly.

Full shape-by-verbosity matrix, example payloads, and the list of custom extension URLs (confidence, evidence, enrichments) live in the [Output formats guide](/guides/output-formats).

## Planned — US Core conformance

Not shipped yet. Once US Core 7.0 profiles are wired up (mandatory fields, must-support extensions, `meta.profile` stamping), we'll add them as a new `format` value rather than repurposing the existing ones. No breaking changes to `fhir_bundle` consumers.

## Code systems we produce

| System                   | URI                                                        | Used for                       |
| ------------------------ | ---------------------------------------------------------- | ------------------------------ |
| RxNorm                   | `http://www.nlm.nih.gov/research/umls/rxnorm`              | Medication canonicalization    |
| SNOMED CT                | `http://snomed.info/sct`                                   | Routes, methods, indications   |
| NCI Thesaurus            | `http://ncicb.nci.nih.gov/xml/owl/EVS/Thesaurus.owl`       | Routes, methods, frequency     |
| ICD-10-CM                | `http://hl7.org/fhir/sid/icd-10-cm`                        | Indications                    |
| FHIR v3 GTS abbreviation | `http://terminology.hl7.org/CodeSystem/v3-GTSAbbreviation` | Frequency (QD, BID, etc.)      |
| FHIR event-timing        | `http://hl7.org/fhir/event-timing`                         | Timing events (MORN, AFT, EVE) |
| FHIR v3 TimingEvent      | `http://terminology.hl7.org/CodeSystem/v3-TimingEvent`     | Timing events (HS, AC, PC)     |
| UCUM                     | `http://unitsofmeasure.org`                                | Durations and dose quantities  |

See the [Enrichments catalog](/enrichments) for how we populate each of these from raw input.