API referenceCodes
Code with ancestors and children
GET /v1/codes/{system}/{code}/hierarchy
GET https://api.healthcare.dev/v1/codes/{system}/{code}/hierarchyThe code, its ancestors (root first) and its direct active children in one call.
Requires an API key: Authorization: Bearer hdev_live_.... See Authentication.
Path parameters
| Name | Type | Required | Description | Example |
|---|---|---|---|---|
system | "icd10cm" | "icd10pcs" | "hcpcs" | yes | Code system | icd10cm |
code | string | yes | Code, with or without the dot | E11.9 |
Query parameters
| Name | Type | Required | Description | Example |
|---|---|---|---|---|
view | "compact" | "full" | no | compact returns only the fields an agent usually needs (fewer tokens); full (default) returns every field | compact |
fields | string | no | Comma-separated record fields to return, e.g. code,display,billable | code,display,billable |
Examples
curl
curl "https://api.healthcare.dev/v1/codes/icd10cm/E11.9/hierarchy" \
-H "Authorization: Bearer $HDEV_API_KEY"TypeScript
const res = await fetch("https://api.healthcare.dev/v1/codes/icd10cm/E11.9/hierarchy", {
headers: { Authorization: `Bearer ${process.env.HDEV_API_KEY}` },
});
const { data, meta } = await res.json();Python
import os
import requests
res = requests.get("https://api.healthcare.dev/v1/codes/icd10cm/E11.9/hierarchy", headers={"Authorization": f"Bearer {os.environ['HDEV_API_KEY']}"})
body = res.json()Try it
Response
Hierarchy
{
"data": {
"parents": [
{
"system": "icd10cm",
"code": "E11.9",
"display": "Type 2 diabetes mellitus without complications",
"description": "Type 2 diabetes mellitus without complications",
"billable": true,
"parent": "E11",
"attributes": {},
"status": "active",
"effective_start": "2015-10-01",
"effective_end": null,
"replaced_by": []
}
],
"code": {
"system": "icd10cm",
"code": "E11.9",
"display": "Type 2 diabetes mellitus without complications",
"description": "Type 2 diabetes mellitus without complications",
"billable": true,
"parent": "E11",
"attributes": {},
"status": "active",
"effective_start": "2015-10-01",
"effective_end": null,
"replaced_by": []
},
"children": [
{
"system": "icd10cm",
"code": "E11.9",
"display": "Type 2 diabetes mellitus without complications",
"description": "Type 2 diabetes mellitus without complications",
"billable": true,
"parent": "E11",
"attributes": {},
"status": "active",
"effective_start": "2015-10-01",
"effective_end": null,
"replaced_by": []
}
]
},
"meta": {
"source": "cms-icd10",
"data_version": "2026.1",
"retrieved_at": "2026-10-24T12:00:00Z",
"license": "Public domain (CMS). Reference data, not medical advice."
},
"links": {
"self": "/v1/codes/icd10cm/E11.9/hierarchy",
"next": null
}
}Fields
| Field | Type | Always present | Description |
|---|---|---|---|
parents | Code[] | yes | |
code | Code | yes | |
children | Code[] | yes |
Errors
Errors are application/problem+json (RFC 9457). Branch on type, not on title. See Errors.
| Status | type | When |
|---|---|---|
| 400 | invalid-request | A parameter or the body failed validation; errors lists each field. |
| 401 | unauthorized | Missing, malformed or revoked API key. |
| 404 | not-found | No record with that id (retired records are still returned). |
| 429 | rate-limited / quota-exceeded | Too many requests per second (retry after Retry-After), or the monthly quota is used up. |
| 503 | dataset-unavailable / unavailable | The dataset has no published version yet, or the service is degraded. |