# Schwartz 2009 bedside eGFR

Schwartz 2009 eGFR

Status: LIVE
Price: $0.005 USDC
`GET /api/calc/schwartz_gfr`
HTML: https://magentlab.com/docs/schwartz-gfr
Markdown: https://magentlab.com/docs/schwartz-gfr.md

Not a medical device. Not a diagnosis, dose, or listing recommendation.

## What it computes

Compute the 2009 Schwartz bedside CKiD eGFR in mL/min/1.73m2 from height and serum creatinine.

## When to use

When an agent needs pediatric eGFR from the 2009 CKiD bedside equation and must not invent CKD-EPI, Cockcroft–Gault, or the 1976 Schwartz k=0.55 formula.

## When not to use

- Not a dosing recommendation. Validated in the pediatric CKiD (Chronic Kidney Disease in Children) cohort; not an adult CKD-EPI or Cockcroft–Gault equation.
- This is the 2009 bedside formula (k=0.413). It is not the 1976 Schwartz k=0.55 formula and does not use cystatin C, BUN, age, or sex.
- Does not assign CKD stages.

## Formula

```
egfr_ml_min_1_73m2 = 0.413 * height_cm / creatinine_mg_dl
```

## Citation

[New equations to estimate GFR in children with CKD](https://doi.org/10.1681/ASN.2008030287)
Schwartz GJ, Muñoz A, Schneider MF, et al.
J Am Soc Nephrol. 2009;20(3):629-637
DOI: [10.1681/ASN.2008030287](https://doi.org/10.1681/ASN.2008030287)

## Worked example

### 140 cm, Scr 1.0 mg/dL

Given: `creatinine_mg_dl=1.0, height_cm=140`

1. eGFR = 0.413 × 140 / 1.0 = 57.82 → 57.8


### 60 in, Scr 1.0 mg/dL

Given: `creatinine_mg_dl=1.0, height_in=60`

1. height_cm = 60 × 2.54 = 152.4
2. eGFR = 0.413 × 152.4 / 1.0 = 62.9412 → 62.9


## Also searched as

- Schwartz 2009
- bedside Schwartz
- CKiD eGFR
- pediatric eGFR
- revised Schwartz
- Schwartz GFR
- 0.413 height creatinine

## Parameters

- `height_cm` (number, optional): Height in centimeters (50-250). Provide height_cm or height_in.
- `height_in` (number, optional): Height in inches (20-98). Converted as cm = in * 2.54.
- `creatinine_mg_dl` (number, optional): Serum creatinine in mg/dL (0.1-20). Provide this or creatinine_umol_l.
- `creatinine_umol_l` (number, optional): Serum creatinine in µmol/L (9-1768). Converted as mg/dL = µmol/L / 88.42.

## Bulk (POST)

POST the same path with a JSON items array. Price is n times the GET unit. Invalid items return HTTP 400 before settlement.

Method: `POST /api/calc/schwartz_gfr`
Max items: 25
Price: unit_amount * n (unit 5000 atomic)
Status: PREVIEW

- 1 to 25 items. Each item uses the same keys as the GET query parameters.
- The first invalid item fails the whole request (index in the 400 JSON). You are not charged.
- HTTP 200 is {count, path, items}. Each items[i] is the GET 200 body for that row.
- Catalog misses (empty matches, found=false) stay paid 200s inside that slot.
- x402 resource URL is this path plus n and body_sha256. Browsers that prefer text/html get the same paywall as GET; Pay retries POST with the same items.

Example request:

```json
{
  "items": [
    {
      "creatinine_mg_dl": "1.0",
      "height_cm": "140"
    },
    {
      "creatinine_mg_dl": "1.0",
      "height_cm": "140"
    }
  ]
}
```

Human paywall (two-item fixture): https://api.magentlab.com/paywall/bulk/schwartz-gfr

Example 200:

```json
{
  "count": 2,
  "path": "/api/calc/schwartz_gfr",
  "items": [
    {
      "units": "mL/min/1.73m2",
      "disclaimer": "Not a medical device. Deterministic published-formula or published-code output for autonomous agents. A licensed clinician remains responsible for patient care and billing submissions.",
      "citation": {
        "authors": "Schwartz GJ, Muñoz A, Schneider MF, et al.",
        "doi": "10.1681/ASN.2008030287",
        "id": "schwartz-2009",
        "source": "J Am Soc Nephrol. 2009;20(3):629-637",
        "title": "New equations to estimate GFR in children with CKD"
      },
      "formula": "schwartz_2009",
      "formula_expression": "egfr_ml_min_1_73m2 = 0.413 * height_cm / creatinine_mg_dl",
      "height_cm": 140.0,
      "creatinine_mg_dl": 1.0,
      "egfr_ml_min_1_73m2": 57.8
    },
    {
      "units": "mL/min/1.73m2",
      "disclaimer": "Not a medical device. Deterministic published-formula or published-code output for autonomous agents. A licensed clinician remains responsible for patient care and billing submissions.",
      "citation": {
        "authors": "Schwartz GJ, Muñoz A, Schneider MF, et al.",
        "doi": "10.1681/ASN.2008030287",
        "id": "schwartz-2009",
        "source": "J Am Soc Nephrol. 2009;20(3):629-637",
        "title": "New equations to estimate GFR in children with CKD"
      },
      "formula": "schwartz_2009",
      "formula_expression": "egfr_ml_min_1_73m2 = 0.413 * height_cm / creatinine_mg_dl",
      "height_cm": 140.0,
      "creatinine_mg_dl": 1.0,
      "egfr_ml_min_1_73m2": 57.8
    }
  ]
}
```

## Response fields

- `formula` (string): schwartz_2009
- `formula_expression` (string): Exact expression used
- `height_cm` (number): Normalized height in cm
- `creatinine_mg_dl` (number): Normalized creatinine in mg/dL
- `egfr_ml_min_1_73m2` (number): Bedside CKiD eGFR, 1 decimal place
- `units` (string): mL/min/1.73m2
- `citation` (object): Schwartz 2009 JASN citation
- `disclaimer` (string): Not-a-device notice

## Example JSON

Frozen fixture. Not a live lookup.

```json
{
  "units": "mL/min/1.73m2",
  "disclaimer": "Not a medical device. Deterministic published-formula or published-code output for autonomous agents. A licensed clinician remains responsible for patient care and billing submissions.",
  "citation": {
    "authors": "Schwartz GJ, Muñoz A, Schneider MF, et al.",
    "doi": "10.1681/ASN.2008030287",
    "id": "schwartz-2009",
    "source": "J Am Soc Nephrol. 2009;20(3):629-637",
    "title": "New equations to estimate GFR in children with CKD"
  },
  "formula": "schwartz_2009",
  "formula_expression": "egfr_ml_min_1_73m2 = 0.413 * height_cm / creatinine_mg_dl",
  "height_cm": 140.0,
  "creatinine_mg_dl": 1.0,
  "egfr_ml_min_1_73m2": 57.8
}
```

## Errors

- HTTP 400 `invalid_height`: height_cm (50-250) or height_in (20-98) is required Returned before settlement; you are not charged.
- HTTP 400 `invalid_creatinine`: creatinine_mg_dl (0.1-20) or creatinine_umol_l (9-1768) is required Returned before settlement; you are not charged.
- HTTP 400 `invalid_items`: POST body must be a JSON object with only an items array Returned before settlement; you are not charged.
- HTTP 400 `invalid_item_count`: items must be an array of 1 to 25 objects Returned before settlement; you are not charged.
- HTTP 400 `invalid_item`: each items entry must be a JSON object Returned before settlement; you are not charged.

Shared HTTP 402 and 503: https://magentlab.com/docs/payments

## Related tools

- [CKD-EPI 2021 eGFR](https://magentlab.com/docs/egfr) — Compute race-free CKD-EPI 2021 creatinine eGFR in mL/min/1.73m2.
- [Cockcroft–Gault CrCl](https://magentlab.com/docs/crcl) — Compute Cockcroft–Gault creatinine clearance in mL/min using total body weight.

## Payment

Required query parameters must be present and valid. Invalid params return HTTP 400 JSON before settlement. magent does not charge. Fix the params, then request a new 402 quote for that complete URL. Catalog misses (empty matches, found=false) are valid paid 200s.

- GET the tool with Accept: application/json (do not send Accept: text/html unless you want the human paywall).
- HTTP 402 means you have not paid. Decode the base64 PAYMENT-REQUIRED header. HTTP 503 is not a new quote.
- Sign EIP-3009 (scheme exact, assetTransferMethod eip3009) with validBefore = now + accepts[0].maxTimeoutSeconds (600 seconds). That window starts when you sign and must cover wallet confirmation plus CDP verify and settle. Magent retries transient facilitator 429/5xx before answering. Do not send upto or batch-settlement payloads; magent does not offer those schemes.
- Retry the same URL with PAYMENT-SIGNATURE (base64 JSON echoing accepted, payload, and extensions when present).
- Success is HTTP 200 JSON plus PAYMENT-RESPONSE. Settlement happens before the tool runs. HTTP 503 settlement_uncertain or settle_failed: retry the same PAYMENT-SIGNATURE. Mint a new nonce only after a new HTTP 402.

- offered `exact` on eip155:8453: Fixed-price USDC on Base. The buyer authorizes the advertised amount (EIP-3009). magent settles before the tool runs (paymentFlow upfront). extra.assetTransferMethod=eip3009 extra.paymentFlow=upfront.

- not offered `upto`: Not offered. Usage-based: buyer authorizes a ceiling, seller settles the actual amount after work. Reserved for a future metered tool. Not for current calculators or code search.
- not offered `batch-settlement`: Not offered. Payment-channel vouchers claimed later in batches. Not the same as POST {items} bulk (that is still exact).

Same-path POST {items} is still scheme exact: one EIP-3009 authorization for n times the GET unit. That is not x402 batch-settlement (payment channels / vouchers).

Shared HTTP 402 and 503 table: https://magentlab.com/docs/payments

Stdio MCP (one process per host): https://magentlab.com/docs/mcp

## Guarantees

- Invalid query parameters return HTTP 400 before settlement. You are not charged.
- Settlement finishes before the tool executes (paymentFlow upfront). Uncertain or failed settlement fails closed (HTTP 503). Retry the same PAYMENT-SIGNATURE.
- HTTP 402 is unpaid only. Do not sign a second authorization because of a 503.
- Execution is timeout-bounded and concurrency-capped.
- Calculator inputs are stored encrypted for allowlisted operators (Magent Console). They are not in public logs, SSH lookups, catalog, or rollups. Request logs store path without query.