Chen kinetic eGFR (KeGFR)

KeGFR

Compute Chen 2013 kinetic eGFR (KeGFR) from two plasma creatinines, the hours between them, a caller-assigned steady-state creatinine and corresponding eGFR/CrCl, and MaxΔPCr/Day. magent does not compute MDRD or CKD-EPI.

LIVE $0.005 USDC GET /api/calc/kegfr

Markdown: /docs/kegfr.md · Canonical: https://magentlab.com/docs/kegfr

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

What it computes

When to use

When plasma creatinine is changing acutely and an agent needs published Chen 2013 KeGFR rather than a CKD-EPI snapshot or a language-model guess. Endpoints should be <48-72 h apart (Chen). Not a dialysis prescription.

When not to use

Not a medical device. Not a CKD-EPI result and not a dialysis prescription.
magent does not compute MDRD or CKD-EPI. The caller assigns steady_state_egfr (5-200) as the corresponding eGFR/CrCl for steady_state_creatinine_mg_dl.
Creatinine is mg/dL only. max_delta_pcr_mg_dl_day is required (Chen usual default 1.5); magent does not omit it. KeGFR is clamped at 0 when the (1 − ratio) term would be negative.

Formula

kegfr_ml_min = (steady_state_creatinine_mg_dl * steady_state_egfr / mean_pcr_mg_dl) * (1 - (24 * delta_pcr_mg_dl) / (delta_hours * max_delta_pcr_mg_dl_day)); mean_pcr_mg_dl = (creatinine_1_mg_dl + creatinine_2_mg_dl) / 2; delta_pcr_mg_dl = creatinine_2_mg_dl - creatinine_1_mg_dl; clamp kegfr_ml_min at 0 when (1 - ratio) is negative (Chen 2013)

Citation

Title: Retooling the Creatinine Clearance Equation to Estimate Kinetic GFR when the Plasma Creatinine Is Changing Acutely
Authors: Chen S
Source: J Am Soc Nephrol. 2013;24(6):877-888
DOI: 10.1681/ASN.2012070653

Worked example

Steady-state Cr 1.0, eGFR 90, 24 h, MaxΔPCr/Day 1.5

Given: creatinine_1_mg_dl=1creatinine_2_mg_dl=1delta_hours=24max_delta_pcr_mg_dl_day=1.5steady_state_creatinine_mg_dl=1steady_state_egfr=90

MeanPCr = (1 + 1) / 2 = 1.0; ΔPCr = 1 - 1 = 0
term = 1 - (24 × 0) / (24 × 1.5) = 1
KeGFR = (1 × 90 / 1.0) × 1 = 90.0 (formula reduces to CrCl)

Also searched as

kinetic GFR
kinetic estimated GFR
Chen KeGFR
kinetic creatinine clearance
non-steady-state GFR
changing plasma creatinine GFR
KeGFR Chen 2013

Try

Opens the live endpoint. Unpaid browser requests show the paywall; agents should send Accept: application/json.

/api/calc/kegfr?creatinine_1_mg_dl=1&creatinine_2_mg_dl=1&delta_hours=24&steady_state_creatinine_mg_dl=1&steady_state_egfr=90&max_delta_pcr_mg_dl_day=1.5

Full URL: https://api.magentlab.com/api/calc/kegfr?creatinine_1_mg_dl=1&creatinine_2_mg_dl=1&delta_hours=24&steady_state_creatinine_mg_dl=1&steady_state_egfr=90&max_delta_pcr_mg_dl_day=1.5

Call

Expect HTTP 402 until you retry with PAYMENT-SIGNATURE. Incomplete query params return HTTP 400 before any quote or charge.

curl -i -H "Accept: application/json" "https://api.magentlab.com/api/calc/kegfr?creatinine_1_mg_dl=1&creatinine_2_mg_dl=1&delta_hours=24&steady_state_creatinine_mg_dl=1&steady_state_egfr=90&max_delta_pcr_mg_dl_day=1.5"

Parameters

Name	Type	Required	Description
`creatinine_1_mg_dl`	number	required	First plasma creatinine in mg/dL (0.1-20). mg/dL only.
`creatinine_2_mg_dl`	number	required	Second plasma creatinine in mg/dL (0.1-20). mg/dL only.
`delta_hours`	number	required	Hours between creatinine_1 and creatinine_2 (1-72). Chen: endpoints <48-72 h apart.
`steady_state_creatinine_mg_dl`	number	required	Steady-state plasma creatinine in mg/dL (0.1-20) corresponding to steady_state_egfr. mg/dL only.
`steady_state_egfr`	number	required	Caller-assigned eGFR/CrCl in mL/min corresponding to steady_state_creatinine_mg_dl (5-200). magent does not compute MDRD or CKD-EPI.
`max_delta_pcr_mg_dl_day`	number	required	Maximum creatinine rise per day in mg/dL (0.5-3). Chen usual default 1.5. Required; magent does not omit it.

Bulk (POST)

POST the same path with a JSON items array. The first item is the GET unit; each additional item is $0.002. Invalid items return HTTP 400 before settlement.

POST /api/calc/kegfr Max 25 unit_amount + extra_item_amount * (n - 1) extra $0.002 PREVIEW

1 to 25 items. Each item uses the same keys as the GET query parameters.
POST of 1 item costs the same as GET. Lists longer than 25: chunk into multiple POSTs. Extra items still execute; do not pad dummy rows.
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 (fixture)

{
  "items": [
    {
      "creatinine_1_mg_dl": "1",
      "creatinine_2_mg_dl": "1",
      "delta_hours": "24",
      "max_delta_pcr_mg_dl_day": "1.5",
      "steady_state_creatinine_mg_dl": "1",
      "steady_state_egfr": "90"
    },
    {
      "creatinine_1_mg_dl": "1",
      "creatinine_2_mg_dl": "1",
      "delta_hours": "24",
      "max_delta_pcr_mg_dl_day": "1.5",
      "steady_state_creatinine_mg_dl": "1",
      "steady_state_egfr": "90"
    }
  ]
}

Open bulk paywall →

Opens a two-item fixture on the API host. Unpaid browsers get the same MetaMask paywall as GET; Pay retries POST with those items.

Example 200 (fixture)

{
  "count": 2,
  "path": "/api/calc/kegfr",
  "items": [
    {
      "units": "mL/min",
      "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": "Chen S",
        "doi": "10.1681/ASN.2012070653",
        "id": "chen-2013",
        "pmid": "23704286",
        "source": "J Am Soc Nephrol. 2013;24(6):877-888",
        "title": "Retooling the Creatinine Clearance Equation to Estimate Kinetic GFR when the Plasma Creatinine Is Changing Acutely"
      },
      "formula": "kegfr",
      "formula_expression": "kegfr_ml_min = (steady_state_creatinine_mg_dl * steady_state_egfr / mean_pcr_mg_dl) * (1 - (24 * delta_pcr_mg_dl) / (delta_hours * max_delta_pcr_mg_dl_day)); mean_pcr_mg_dl = (creatinine_1_mg_dl + creatinine_2_mg_dl) / 2; delta_pcr_mg_dl = creatinine_2_mg_dl - creatinine_1_mg_dl; clamp kegfr_ml_min at 0 when (1 - ratio) is negative (Chen 2013)",
      "creatinine_1_mg_dl": 1.0,
      "creatinine_2_mg_dl": 1.0,
      "delta_hours": 24.0,
      "delta_pcr_mg_dl": 0.0,
      "kegfr_ml_min": 90.0,
      "max_delta_pcr_mg_dl_day": 1.5,
      "mean_pcr_mg_dl": 1.0,
      "steady_state_creatinine_mg_dl": 1.0,
      "steady_state_egfr": 90.0
    },
    {
      "units": "mL/min",
      "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": "Chen S",
        "doi": "10.1681/ASN.2012070653",
        "id": "chen-2013",
        "pmid": "23704286",
        "source": "J Am Soc Nephrol. 2013;24(6):877-888",
        "title": "Retooling the Creatinine Clearance Equation to Estimate Kinetic GFR when the Plasma Creatinine Is Changing Acutely"
      },
      "formula": "kegfr",
      "formula_expression": "kegfr_ml_min = (steady_state_creatinine_mg_dl * steady_state_egfr / mean_pcr_mg_dl) * (1 - (24 * delta_pcr_mg_dl) / (delta_hours * max_delta_pcr_mg_dl_day)); mean_pcr_mg_dl = (creatinine_1_mg_dl + creatinine_2_mg_dl) / 2; delta_pcr_mg_dl = creatinine_2_mg_dl - creatinine_1_mg_dl; clamp kegfr_ml_min at 0 when (1 - ratio) is negative (Chen 2013)",
      "creatinine_1_mg_dl": 1.0,
      "creatinine_2_mg_dl": 1.0,
      "delta_hours": 24.0,
      "delta_pcr_mg_dl": 0.0,
      "kegfr_ml_min": 90.0,
      "max_delta_pcr_mg_dl_day": 1.5,
      "mean_pcr_mg_dl": 1.0,
      "steady_state_creatinine_mg_dl": 1.0,
      "steady_state_egfr": 90.0
    }
  ]
}

Response

Field	Type	Description
`formula`	string	kegfr
`formula_expression`	string	Exact Chen 2013 KeGFR expression, including mean, signed delta, and clamp
`creatinine_1_mg_dl`	number	First plasma creatinine in mg/dL
`creatinine_2_mg_dl`	number	Second plasma creatinine in mg/dL
`delta_hours`	number	Hours between the two creatinines
`steady_state_creatinine_mg_dl`	number	Steady-state plasma creatinine in mg/dL
`steady_state_egfr`	number	Caller-assigned corresponding eGFR/CrCl in mL/min
`max_delta_pcr_mg_dl_day`	number	Maximum creatinine rise per day in mg/dL
`mean_pcr_mg_dl`	number	Arithmetic mean of creatinine_1_mg_dl and creatinine_2_mg_dl
`delta_pcr_mg_dl`	number	Signed creatinine_2_mg_dl minus creatinine_1_mg_dl
`kegfr_ml_min`	number	Kinetic eGFR in mL/min, 1 decimal. Clamped at 0. Not a CKD-EPI result.
`units`	string	mL/min
`citation`	object	Chen J Am Soc Nephrol 2013 citation
`disclaimer`	string	Not-a-device notice

Example JSON

Machine form of the same example. Frozen fixture. Not a live lookup.

{
  "units": "mL/min",
  "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": "Chen S",
    "doi": "10.1681/ASN.2012070653",
    "id": "chen-2013",
    "pmid": "23704286",
    "source": "J Am Soc Nephrol. 2013;24(6):877-888",
    "title": "Retooling the Creatinine Clearance Equation to Estimate Kinetic GFR when the Plasma Creatinine Is Changing Acutely"
  },
  "formula": "kegfr",
  "formula_expression": "kegfr_ml_min = (steady_state_creatinine_mg_dl * steady_state_egfr / mean_pcr_mg_dl) * (1 - (24 * delta_pcr_mg_dl) / (delta_hours * max_delta_pcr_mg_dl_day)); mean_pcr_mg_dl = (creatinine_1_mg_dl + creatinine_2_mg_dl) / 2; delta_pcr_mg_dl = creatinine_2_mg_dl - creatinine_1_mg_dl; clamp kegfr_ml_min at 0 when (1 - ratio) is negative (Chen 2013)",
  "creatinine_1_mg_dl": 1.0,
  "creatinine_2_mg_dl": 1.0,
  "delta_hours": 24.0,
  "delta_pcr_mg_dl": 0.0,
  "kegfr_ml_min": 90.0,
  "max_delta_pcr_mg_dl_day": 1.5,
  "mean_pcr_mg_dl": 1.0,
  "steady_state_creatinine_mg_dl": 1.0,
  "steady_state_egfr": 90.0
}

Client errors (HTTP 400)

Invalid params return 400 without charge. Shared HTTP 402 and 503 meanings: Payments.

HTTP	Code	When
400	`invalid_kegfr`	creatinine_1_mg_dl and creatinine_2_mg_dl must be 0.1-20, delta_hours 1-72, and max_delta_pcr_mg_dl_day 0.5-3 (Chen 2013 KeGFR). Returned before settlement; you are not charged.
400	`invalid_egfr`	egfr_ml_min_1_73m2 must be a number from 5 to 200 (caller-assigned eGFR; magent does not compute MDRD or CKD-EPI). Returned before settlement; you are not charged.
400	`invalid_items`	POST body must be a JSON object with only an items array Returned before settlement; you are not charged.
400	`invalid_item_count`	items must be an array of 1 to 25 objects Returned before settlement; you are not charged.
400	`invalid_item`	each items entry must be a JSON object Returned before settlement; you are not charged.

Related tools

CKD-EPI 2021 eGFR — Compute race-free CKD-EPI 2021 creatinine eGFR in mL/min/1.73m2.
Cockcroft–Gault CrCl — Compute Cockcroft–Gault creatinine clearance in mL/min using total body weight.

Payment

Unpaid requests return HTTP 402 even if query parameters or POST items are missing or invalid, so CDP and agents can index the path. After a PAYMENT-SIGNATURE, 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. Unpaid valid requests return HTTP 402 with a base64 PAYMENT-REQUIRED header. HTTP 503 is not a new quote: retry the same PAYMENT-SIGNATURE. Full handshake and shared payment errors: Payments. Stdio MCP: /docs/mcp.

Guarantees

HTTP 402 is unpaid, including a missing query. After PAYMENT-SIGNATURE, invalid parameters return HTTP 400 before settlement. You are not charged. HTTP 402 never includes the tool JSON.
exact: settlement finishes before the tool (paymentFlow upfront). batch-settlement: verify/deposit before the tool; chargedCumulativeAmount commits after HTTP 2xx. 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.