Electrolytes / glucose · LIVE

Acid-base assessment (Berend)

Apply the Berend 2014 physiological stepwise assessment: pH acidemia or alkalemia, Table 1 primary metabolic versus respiratory process, anion gap, optional albumin-corrected gap, and printed delta-delta.

LIVE $0.005 USDC GET /api/calc/abg

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

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

What it computes

Apply the Berend 2014 physiological stepwise assessment: pH acidemia or alkalemia, Table 1 primary metabolic versus respiratory process, anion gap, optional albumin-corrected gap, and printed delta-delta.

When to use

When an agent has arterial pH, PaCO2, bicarbonate, sodium, and chloride and needs Berend 2014 stepwise labels and numeric intermediates.

When not to use

• Not a medical device and not a diagnosis. magent does not assay arterial blood gas, assign a cause, or replace clinical context.
• Not a ventilator setting, oxygen prescription, or bicarbonate dose.
• Expected PaCO2 in metabolic acidosis is the Table 1 Winters secondary response (1.5×HCO3+8±2), not a treatment target. Standalone Winters is the related winters tool.
• Anion gap uses Na−Cl−HCO3. High versus normal uses Berend's example upper reference of 12 mmol/L; the paper states the laboratory range is analyzer-specific.
• Albumin correction uses Figure 1 (2.5 mmol/L per 1 g/dL decrease). Berend does not print a reference albumin; this tool uses 4.0 g/dL as the decrement baseline and does not reverse-correct hyperalbuminemia.
• Delta-delta is returned only when the anion gap is high. Both ketoacidosis (1:1) and lactic (0.6) printed equations are returned; magent does not pick one from lactate.
• Does not compute A-a difference, osmolal gap, or urinary anion gap.

Formula

Berend 2014: acidemia if pH<7.38; alkalemia if pH>7.42; metabolic acidosis if pH<7.38 and HCO3<22; metabolic alkalosis if pH>7.42 and HCO3>26; respiratory acidosis if pH<7.38 and PaCO2>42; respiratory alkalosis if pH>7.42 and PaCO2<38; anion_gap=Na-Cl-HCO3 (high if >12); albumin-corrected AG=AG+2.5*(4.0-albumin) when albumin<4.0 g/dL; metabolic acidosis expected PaCO2=1.5*HCO3+8±2; metabolic alkalosis expected PaCO2=0.7*(HCO3-24)+40±2; acute respiratory acidosis HCO3 +1 per 10 mm Hg PaCO2 above 40; chronic +4 to +5; acute respiratory alkalosis HCO3 -2 per 10 mm Hg PaCO2 below 40; chronic -4 to -5; ketoacidosis delta-delta=ΔAG-ΔHCO3; lactic delta-delta=0.6*ΔAG-ΔHCO3 (simple if -5 to 5)

Citation

Title

Physiological Approach to Assessment of Acid-Base Disturbances

Authors

Berend K, de Vries APJ, Gans ROB

Source

N Engl J Med. 2014;371:1434-1445

DOI

10.1056/NEJMra1003327

Worked example

Also searched as

• Berend acid-base
• acidemia alkalemia
• stepwise acid-base
• physiological acid-base
• delta delta anion gap
• albumin-corrected anion gap
• arterial blood gas assessment

Try

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

/api/calc/abg?ph=7.28&paco2_mm_hg=39&bicarbonate_mmol_l=18&sodium_mmol_l=135&chloride_mmol_l=115

Full URL: https://api.magentlab.com/api/calc/abg?ph=7.28&paco2_mm_hg=39&bicarbonate_mmol_l=18&sodium_mmol_l=135&chloride_mmol_l=115

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/abg?ph=7.28&paco2_mm_hg=39&bicarbonate_mmol_l=18&sodium_mmol_l=135&chloride_mmol_l=115"

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/abg 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": [
    {
      "bicarbonate_mmol_l": "18",
      "chloride_mmol_l": "115",
      "paco2_mm_hg": "39",
      "ph": "7.28",
      "sodium_mmol_l": "135"
    },
    {
      "bicarbonate_mmol_l": "18",
      "chloride_mmol_l": "115",
      "paco2_mm_hg": "39",
      "ph": "7.28",
      "sodium_mmol_l": "135"
    }
  ]
}

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/abg",
  "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": "Berend K, de Vries APJ, Gans ROB",
        "doi": "10.1056/NEJMra1003327",
        "id": "berend-2014-acid-base",
        "pmid": "25295502",
        "source": "N Engl J Med. 2014;371:1434-1445",
        "title": "Physiological Approach to Assessment of Acid-Base Disturbances"
      },
      "formula": "abg",
      "formula_expression": "Berend 2014: acidemia if pH<7.38; alkalemia if pH>7.42; metabolic acidosis if pH<7.38 and HCO3<22; metabolic alkalosis if pH>7.42 and HCO3>26; respiratory acidosis if pH<7.38 and PaCO2>42; respiratory alkalosis if pH>7.42 and PaCO2<38; anion_gap=Na-Cl-HCO3 (high if >12); albumin-corrected AG=AG+2.5*(4.0-albumin) when albumin<4.0 g/dL; metabolic acidosis expected PaCO2=1.5*HCO3+8±2; metabolic alkalosis expected PaCO2=0.7*(HCO3-24)+40±2; acute respiratory acidosis HCO3 +1 per 10 mm Hg PaCO2 above 40; chronic +4 to +5; acute respiratory alkalosis HCO3 -2 per 10 mm Hg PaCO2 below 40; chronic -4 to -5; ketoacidosis delta-delta=ΔAG-ΔHCO3; lactic delta-delta=0.6*ΔAG-ΔHCO3 (simple if -5 to 5)",
      "paco2_mm_hg": 39.0,
      "secondary_response": "additional respiratory acidosis",
      "anion_gap_class": "normal",
      "anion_gap_mmol_l": 2.0,
      "bicarbonate_mmol_l": 18.0,
      "chloride_mmol_l": 115.0,
      "criteria": [
        {
          "value": 7.28,
          "factor": "acidemia",
          "met": true
        },
        {
          "value": 7.28,
          "factor": "alkalemia",
          "met": false
        },
        {
          "value": 18.0,
          "factor": "metabolic_acidosis",
          "met": true
        },
        {
          "value": 18.0,
          "factor": "metabolic_alkalosis",
          "met": false
        },
        {
          "value": 39.0,
          "factor": "respiratory_acidosis",
          "met": false
        },
        {
          "value": 39.0,
          "factor": "respiratory_alkalosis",
          "met": false
        },
        {
          "value": 2.0,
          "factor": "high_anion_gap",
          "met": false
        },
        {
          "value": 2.0,
          "factor": "normal_anion_gap",
          "met": true
        }
      ],
      "disorders": [
        "acidemia",
        "metabolic acidosis",
        "normal anion-gap acidosis",
        "additional respiratory acidosis"
      ],
      "ph": 7.28,
      "ph_status": "acidemia",
      "primary_process": "metabolic acidosis",
      "sodium_mmol_l": 135.0,
      "expected_paco2_high_mm_hg": 37.0,
      "expected_paco2_low_mm_hg": 33.0,
      "expected_paco2_mm_hg": 35.0
    },
    {
      "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": "Berend K, de Vries APJ, Gans ROB",
        "doi": "10.1056/NEJMra1003327",
        "id": "berend-2014-acid-base",
        "pmid": "25295502",
        "source": "N Engl J Med. 2014;371:1434-1445",
        "title": "Physiological Approach to Assessment of Acid-Base Disturbances"
      },
      "formula": "abg",
      "formula_expression": "Berend 2014: acidemia if pH<7.38; alkalemia if pH>7.42; metabolic acidosis if pH<7.38 and HCO3<22; metabolic alkalosis if pH>7.42 and HCO3>26; respiratory acidosis if pH<7.38 and PaCO2>42; respiratory alkalosis if pH>7.42 and PaCO2<38; anion_gap=Na-Cl-HCO3 (high if >12); albumin-corrected AG=AG+2.5*(4.0-albumin) when albumin<4.0 g/dL; metabolic acidosis expected PaCO2=1.5*HCO3+8±2; metabolic alkalosis expected PaCO2=0.7*(HCO3-24)+40±2; acute respiratory acidosis HCO3 +1 per 10 mm Hg PaCO2 above 40; chronic +4 to +5; acute respiratory alkalosis HCO3 -2 per 10 mm Hg PaCO2 below 40; chronic -4 to -5; ketoacidosis delta-delta=ΔAG-ΔHCO3; lactic delta-delta=0.6*ΔAG-ΔHCO3 (simple if -5 to 5)",
      "paco2_mm_hg": 39.0,
      "secondary_response": "additional respiratory acidosis",
      "anion_gap_class": "normal",
      "anion_gap_mmol_l": 2.0,
      "bicarbonate_mmol_l": 18.0,
      "chloride_mmol_l": 115.0,
      "criteria": [
        {
          "value": 7.28,
          "factor": "acidemia",
          "met": true
        },
        {
          "value": 7.28,
          "factor": "alkalemia",
          "met": false
        },
        {
          "value": 18.0,
          "factor": "metabolic_acidosis",
          "met": true
        },
        {
          "value": 18.0,
          "factor": "metabolic_alkalosis",
          "met": false
        },
        {
          "value": 39.0,
          "factor": "respiratory_acidosis",
          "met": false
        },
        {
          "value": 39.0,
          "factor": "respiratory_alkalosis",
          "met": false
        },
        {
          "value": 2.0,
          "factor": "high_anion_gap",
          "met": false
        },
        {
          "value": 2.0,
          "factor": "normal_anion_gap",
          "met": true
        }
      ],
      "disorders": [
        "acidemia",
        "metabolic acidosis",
        "normal anion-gap acidosis",
        "additional respiratory acidosis"
      ],
      "ph": 7.28,
      "ph_status": "acidemia",
      "primary_process": "metabolic acidosis",
      "sodium_mmol_l": 135.0,
      "expected_paco2_high_mm_hg": 37.0,
      "expected_paco2_low_mm_hg": 33.0,
      "expected_paco2_mm_hg": 35.0
    }
  ]
}

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": "Berend K, de Vries APJ, Gans ROB",
    "doi": "10.1056/NEJMra1003327",
    "id": "berend-2014-acid-base",
    "pmid": "25295502",
    "source": "N Engl J Med. 2014;371:1434-1445",
    "title": "Physiological Approach to Assessment of Acid-Base Disturbances"
  },
  "formula": "abg",
  "formula_expression": "Berend 2014: acidemia if pH<7.38; alkalemia if pH>7.42; metabolic acidosis if pH<7.38 and HCO3<22; metabolic alkalosis if pH>7.42 and HCO3>26; respiratory acidosis if pH<7.38 and PaCO2>42; respiratory alkalosis if pH>7.42 and PaCO2<38; anion_gap=Na-Cl-HCO3 (high if >12); albumin-corrected AG=AG+2.5*(4.0-albumin) when albumin<4.0 g/dL; metabolic acidosis expected PaCO2=1.5*HCO3+8±2; metabolic alkalosis expected PaCO2=0.7*(HCO3-24)+40±2; acute respiratory acidosis HCO3 +1 per 10 mm Hg PaCO2 above 40; chronic +4 to +5; acute respiratory alkalosis HCO3 -2 per 10 mm Hg PaCO2 below 40; chronic -4 to -5; ketoacidosis delta-delta=ΔAG-ΔHCO3; lactic delta-delta=0.6*ΔAG-ΔHCO3 (simple if -5 to 5)",
  "paco2_mm_hg": 39.0,
  "secondary_response": "additional respiratory acidosis",
  "anion_gap_class": "normal",
  "anion_gap_mmol_l": 2.0,
  "bicarbonate_mmol_l": 18.0,
  "chloride_mmol_l": 115.0,
  "criteria": [
    {
      "value": 7.28,
      "factor": "acidemia",
      "met": true
    },
    {
      "value": 7.28,
      "factor": "alkalemia",
      "met": false
    },
    {
      "value": 18.0,
      "factor": "metabolic_acidosis",
      "met": true
    },
    {
      "value": 18.0,
      "factor": "metabolic_alkalosis",
      "met": false
    },
    {
      "value": 39.0,
      "factor": "respiratory_acidosis",
      "met": false
    },
    {
      "value": 39.0,
      "factor": "respiratory_alkalosis",
      "met": false
    },
    {
      "value": 2.0,
      "factor": "high_anion_gap",
      "met": false
    },
    {
      "value": 2.0,
      "factor": "normal_anion_gap",
      "met": true
    }
  ],
  "disorders": [
    "acidemia",
    "metabolic acidosis",
    "normal anion-gap acidosis",
    "additional respiratory acidosis"
  ],
  "ph": 7.28,
  "ph_status": "acidemia",
  "primary_process": "metabolic acidosis",
  "sodium_mmol_l": 135.0,
  "expected_paco2_high_mm_hg": 37.0,
  "expected_paco2_low_mm_hg": 33.0,
  "expected_paco2_mm_hg": 35.0
}

Client errors (HTTP 400)

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

Related tools

• Winters' formula — Compute expected arterial PCO2 in metabolic acidosis from plasma bicarbonate using the Albert–Winters 1967 formula.
• Anion gap — Compute the serum anion gap from sodium, chloride, and bicarbonate, with or without potassium, using the Emmett–Narins 1977 formulas. formula is required.

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.