{
  "slug": "delta-gap-ratio",
  "title": "Delta Gap / Delta Ratio Calculator",
  "heading": "Delta Gap and Delta Ratio Calculator",
  "category": "fitness-health",
  "url": "https://www.revenuelab.fyi/toolbox/delta-gap-ratio",
  "summary": "Detect a hidden second metabolic process alongside an anion gap acidosis.",
  "description": "The delta ratio compares the rise in anion gap to the fall in bicarbonate to reveal whether a mixed acid-base disorder is hiding alongside an obvious anion-gap metabolic acidosis. A ratio between roughly 1 and 2 suggests a pure anion-gap metabolic acidosis (the gap rose about as much as the bicarbonate fell, as expected from simple buffering). A ratio below 1 suggests a concurrent non-gap (hyperchloremic) metabolic acidosis — bicarbonate fell more than the gap rose, meaning something is consuming bicarbonate beyond what the elevated anion gap alone explains, common with concurrent diarrhea or renal tubular acidosis in a patient who also has ketoacidosis or lactic acidosis. A ratio above 2 suggests a concurrent metabolic alkalosis or a pre-existing elevated bicarbonate — the bicarbonate didn't fall as much as expected given the size of the gap, sometimes seen in vomiting-plus-ketoacidosis or chronic compensated respiratory acidosis. This is a pattern-recognition tool that requires a reliable baseline (usually assumed normal) HCO3 and anion gap. This tool is for education and workflow support only — not medical advice. Always verify results with a clinician and use clinical judgment alongside your institution's protocols.",
  "formula": "Delta gap = measured anion gap − 12 (assumed normal). Delta ratio = delta gap ÷ (24 − measured HCO3).",
  "dateModified": "2026-09-30",
  "run_url": "https://www.revenuelab.fyi/api/public/calc?tool=delta-gap-ratio",
  "inputs": [
    {
      "id": "na",
      "label": "Sodium",
      "kind": "number",
      "hint": null,
      "default": 138,
      "unit": "mEq/L",
      "min": 100,
      "max": 170
    },
    {
      "id": "cl",
      "label": "Chloride",
      "kind": "number",
      "hint": null,
      "default": 96,
      "unit": "mEq/L",
      "min": 70,
      "max": 130
    },
    {
      "id": "hco3",
      "label": "Bicarbonate (HCO3)",
      "kind": "number",
      "hint": null,
      "default": 10,
      "unit": "mEq/L",
      "min": 2,
      "max": 40
    },
    {
      "id": "normalAg",
      "label": "Assumed normal anion gap",
      "kind": "number",
      "hint": null,
      "default": 12,
      "unit": "mEq/L",
      "min": 4,
      "max": 16
    }
  ],
  "outputs": [
    {
      "id": "ag",
      "label": "Anion gap",
      "format": "decimal",
      "hint": null,
      "primary": true
    },
    {
      "id": "deltaGap",
      "label": "Delta gap",
      "format": "decimal",
      "hint": null,
      "primary": false
    },
    {
      "id": "deltaRatio",
      "label": "Delta ratio",
      "format": "decimal",
      "hint": null,
      "primary": false
    },
    {
      "id": "interpretation",
      "label": "Interpretation",
      "format": "raw",
      "hint": null,
      "primary": false
    }
  ],
  "worked_example": {
    "inputs": [
      "Sodium: 138 mEq/L",
      "Chloride: 96 mEq/L",
      "Bicarbonate (HCO3): 10 mEq/L",
      "Assumed normal anion gap: 12 mEq/L"
    ],
    "outputs": [
      "Anion gap: 32",
      "Delta gap: 20",
      "Delta ratio: 1.43",
      "Interpretation: Pure anion-gap metabolic acidosis"
    ]
  },
  "how_to": {
    "title": "How to use this",
    "steps": [
      "Enter sodium (mEq/L).",
      "Enter chloride (mEq/L).",
      "Enter bicarbonate (hco3) (mEq/L).",
      "Enter assumed normal anion gap (mEq/L).",
      "Read your anion gap on the right — it updates as you type.",
      "Hit Share to keep the scenario or send it to someone."
    ]
  },
  "scenarios": [
    {
      "name": "Conservative",
      "description": "Lower-end numbers — what if things land soft?",
      "values": {
        "na": 100,
        "cl": 70,
        "hco3": 6,
        "normalAg": 7
      }
    },
    {
      "name": "Typical",
      "description": "Defaults — the most common real-world setup.",
      "values": {
        "na": 138,
        "cl": 96,
        "hco3": 10,
        "normalAg": 12
      }
    },
    {
      "name": "Ambitious",
      "description": "Higher-end numbers — what if things really pop?",
      "values": {
        "na": 170,
        "cl": 130,
        "hco3": 16,
        "normalAg": 16
      }
    }
  ],
  "limitations": [
    "Population formulas describe averages; individual bodies vary, especially at the extremes of height, age, or muscle mass.",
    "Results do not account for medical conditions, medication, or pregnancy.",
    "Use this as a directional reference, not a diagnosis — talk to a clinician before acting on it."
  ],
  "faq": [
    {
      "q": "What does a delta ratio below 1 tell me?",
      "a": "It tells you bicarbonate has fallen more than the anion gap rise alone can explain, pointing to an additional non-gap (hyperchloremic) metabolic acidosis on top of the gap acidosis — for example, a patient in diabetic ketoacidosis who has also had significant diarrhea or large-volume saline resuscitation."
    },
    {
      "q": "What does a delta ratio above 2 mean?",
      "a": "It suggests bicarbonate is higher than expected given the size of the anion gap, pointing to a concurrent metabolic alkalosis or a chronically elevated baseline bicarbonate (as in chronic respiratory acidosis with renal compensation), partially masking the expected bicarbonate drop from the gap acidosis."
    },
    {
      "q": "Why assume a normal anion gap of 12?",
      "a": "12 mEq/L is a commonly used average baseline for a 'normal' unmeasured anion gap, though normal ranges vary by lab and by whether potassium is included in the calculation (roughly 8-12 without potassium, 10-16 with it). Using your lab's actual reference range as the 'normal' input improves accuracy over assuming a fixed value."
    },
    {
      "q": "Is the delta ratio reliable in every patient?",
      "a": "It's a useful pattern-recognition tool but has real limitations — it assumes a fairly stable relationship between gap rise and bicarbonate fall that doesn't always hold, particularly with severe acidosis, renal failure, or multiple simultaneous processes. Use it to raise suspicion for a mixed disorder, then confirm with full clinical correlation, not as a standalone diagnosis."
    }
  ],
  "related": [
    "https://www.revenuelab.fyi/toolbox/abg-interpretation",
    "https://www.revenuelab.fyi/toolbox/winters-formula",
    "https://www.revenuelab.fyi/toolbox/osmolar-gap"
  ],
  "license": "CC-BY-4.0",
  "citation": "RevenueLab — Delta Gap / Delta Ratio Calculator (https://www.revenuelab.fyi/toolbox/delta-gap-ratio)"
}