Hematology · LIVE

Sickle RBC exchange

Compute replacement packed-RBC volume for sickle red-cell exchange from Nadler 1962 adult blood volume and exponential remaining-fraction washout Y/Y0 = e^(−X), with caller-supplied hematocrits and HbS percents.

LIVE $0.005 USDC GET /api/calc/sickle_rbc_exchange

Markdown: /docs/sickle-rbc-exchange.md · Canonical: https://magentlab.com/docs/sickle-rbc-exchange

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

What it computes

Compute replacement packed-RBC volume for sickle red-cell exchange from Nadler 1962 adult blood volume and exponential remaining-fraction washout Y/Y0 = e^(−X), with caller-supplied hematocrits and HbS percents.

When to use

When an agent needs published Nadler TBV plus remaining-fraction washout and must not invent a replacement volume, force a 30% HbS target, or write an apheresis order.

When not to use

• Not a medical device. magent does not write an apheresis prescription, choose a machine protocol, or run vendor FCR or end-hematocrit software.
• AABB 2018 usual acute-exchange language is HbS not more than 30% and avoiding hyperviscosity. That is not a forced target; the caller sends target_hbs_percent.
• Adult Nadler 1962 blood volume only (male and female equations; H meters, W kg). Not a 70 mL/kg rule. Exponential remaining-fraction washout only; not a linear (1 − FCR) volume.
• Replacement hematocrit is caller-supplied (typical additive units about 60 percent). magent does not assay the unit or choose a product.

Formula

TBV_L male = 0.3669 * H^3 + 0.03219 * W + 0.6041; female = 0.3561 * H^3 + 0.03308 * W + 0.1833 (H meters, W kg). patient_rbc_volume_ml = TBV_mL * hematocrit_percent/100. FCR = target_hbs_percent/initial_hbs_percent. X = -ln(FCR). replacement_prbc_ml = patient_rbc_volume_ml * X / (replacement_hct_percent/100)

Citation

Title

Prediction of blood volume in normal human adults

Authors

Nadler SB, Hidalgo JH, Bloch T

Source

Surgery. 1962;51(2):224-232

DOI

none

Worked example

Also searched as

• sickle cell RBC exchange
• red cell exchange volume
• HbS washout
• Nadler RBC exchange
• sickle cell exchange transfusion
• remaining fraction washout
• pRBC replacement volume
• HbS fraction remaining

Try

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

/api/calc/sickle_rbc_exchange?sex=male&height_cm=170&weight_kg=70&hematocrit_percent=30&initial_hbs_percent=90&target_hbs_percent=30&replacement_hct_percent=60

Full URL: https://api.magentlab.com/api/calc/sickle_rbc_exchange?sex=male&height_cm=170&weight_kg=70&hematocrit_percent=30&initial_hbs_percent=90&target_hbs_percent=30&replacement_hct_percent=60

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/sickle_rbc_exchange?sex=male&height_cm=170&weight_kg=70&hematocrit_percent=30&initial_hbs_percent=90&target_hbs_percent=30&replacement_hct_percent=60"

Parameters

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/sickle_rbc_exchange 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": [
    {
      "height_cm": "170",
      "hematocrit_percent": "30",
      "initial_hbs_percent": "90",
      "replacement_hct_percent": "60",
      "sex": "male",
      "target_hbs_percent": "30",
      "weight_kg": "70"
    },
    {
      "height_cm": "170",
      "hematocrit_percent": "30",
      "initial_hbs_percent": "90",
      "replacement_hct_percent": "60",
      "sex": "male",
      "target_hbs_percent": "30",
      "weight_kg": "70"
    }
  ]
}

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/sickle_rbc_exchange",
  "items": [
    {
      "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": "Nadler SB, Hidalgo JH, Bloch T",
        "id": "nadler-1962",
        "pmid": "21936146",
        "source": "Surgery. 1962;51(2):224-232",
        "title": "Prediction of blood volume in normal human adults"
      },
      "formula": "nadler_exponential_washout",
      "formula_expression": "TBV_L male = 0.3669 * H^3 + 0.03219 * W + 0.6041; female = 0.3561 * H^3 + 0.03308 * W + 0.1833 (H meters, W kg). patient_rbc_volume_ml = TBV_mL * hematocrit_percent/100. FCR = target_hbs_percent/initial_hbs_percent. X = -ln(FCR). replacement_prbc_ml = patient_rbc_volume_ml * X / (replacement_hct_percent/100)",
      "weight_kg": 70.0,
      "sex": "male",
      "hematocrit_percent": 30.0,
      "height_cm": 170.0,
      "blood_volume_ml": 4660,
      "blood_volume_l": 4.66,
      "fcr": 0.3333,
      "initial_hbs_percent": 90.0,
      "patient_rbc_volume_ml": 1398.0,
      "rbc_volumes_exchanged": 1.0986,
      "replacement_hct_percent": 60.0,
      "replacement_prbc_ml": 2559.8,
      "target_hbs_percent": 30.0
    },
    {
      "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": "Nadler SB, Hidalgo JH, Bloch T",
        "id": "nadler-1962",
        "pmid": "21936146",
        "source": "Surgery. 1962;51(2):224-232",
        "title": "Prediction of blood volume in normal human adults"
      },
      "formula": "nadler_exponential_washout",
      "formula_expression": "TBV_L male = 0.3669 * H^3 + 0.03219 * W + 0.6041; female = 0.3561 * H^3 + 0.03308 * W + 0.1833 (H meters, W kg). patient_rbc_volume_ml = TBV_mL * hematocrit_percent/100. FCR = target_hbs_percent/initial_hbs_percent. X = -ln(FCR). replacement_prbc_ml = patient_rbc_volume_ml * X / (replacement_hct_percent/100)",
      "weight_kg": 70.0,
      "sex": "male",
      "hematocrit_percent": 30.0,
      "height_cm": 170.0,
      "blood_volume_ml": 4660,
      "blood_volume_l": 4.66,
      "fcr": 0.3333,
      "initial_hbs_percent": 90.0,
      "patient_rbc_volume_ml": 1398.0,
      "rbc_volumes_exchanged": 1.0986,
      "replacement_hct_percent": 60.0,
      "replacement_prbc_ml": 2559.8,
      "target_hbs_percent": 30.0
    }
  ]
}

Response

Example JSON

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

{
  "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": "Nadler SB, Hidalgo JH, Bloch T",
    "id": "nadler-1962",
    "pmid": "21936146",
    "source": "Surgery. 1962;51(2):224-232",
    "title": "Prediction of blood volume in normal human adults"
  },
  "formula": "nadler_exponential_washout",
  "formula_expression": "TBV_L male = 0.3669 * H^3 + 0.03219 * W + 0.6041; female = 0.3561 * H^3 + 0.03308 * W + 0.1833 (H meters, W kg). patient_rbc_volume_ml = TBV_mL * hematocrit_percent/100. FCR = target_hbs_percent/initial_hbs_percent. X = -ln(FCR). replacement_prbc_ml = patient_rbc_volume_ml * X / (replacement_hct_percent/100)",
  "weight_kg": 70.0,
  "sex": "male",
  "hematocrit_percent": 30.0,
  "height_cm": 170.0,
  "blood_volume_ml": 4660,
  "blood_volume_l": 4.66,
  "fcr": 0.3333,
  "initial_hbs_percent": 90.0,
  "patient_rbc_volume_ml": 1398.0,
  "rbc_volumes_exchanged": 1.0986,
  "replacement_hct_percent": 60.0,
  "replacement_prbc_ml": 2559.8,
  "target_hbs_percent": 30.0
}

Client errors (HTTP 400)

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

Related tools

• Nadler blood volume — Compute Nadler 1962 predicted blood volume in liters and milliliters from height, weight, and sex.
• Allowable blood loss — Compute Gross 1983 dilution-corrected allowable blood loss from a caller-supplied estimated blood volume and initial versus target hematocrit.
• Kaplan plasma volume — Compute Kaplan 1990 estimated plasma volume for therapeutic plasma exchange from weight and hematocrit as a percent, returning one plasma volume in liters and milliliters.

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.