Anion gap calculator

What the serum anion gap measures and which inputs you need

Send required fields sodium, chloride, and bicarbonate as finite numbers; aliases such as na, cl, hco3, bicarb, and total_co2 are accepted when documented. Optional normal_albumin defaults to four point zero grams per decilitre. Any negative electrolyte or negative albumin fails with invalid_input because negative serum values are not a valid panel for this calculator. Identical inputs always yield identical JSON because the path is pure arithmetic with no network, no model, no random seed, and no wall clock.

Reading anion_gap, albumin correction, and response fields

On success the response echoes sodium, chloride, bicarbonate, albumin, and normal_albumin with stable rounding, sets unit_electrolytes to mEq/L and unit_albumin to g/dL, and reports albumin_provided so you know whether the client sent albumin or the default was applied. The anion_gap field is sodium minus chloride minus bicarbonate. The albumin_correction field is two point five times normal_albumin minus albumin, the additive term in milliequivalents per litre. The anion_gap_corrected field is anion_gap plus that correction, so hypoalbuminemia raises the corrected gap toward what it would have been at normal albumin. correction_factor is always two point five, formula restates both equations as a single teaching string, and method is always serum_anion_gap_albumin_corrected so downstream code can branch without sniffing shapes. Use anion_gap alone when you only need the classical panel math; use anion_gap_corrected and albumin_correction when reviewing low-albumin patients or teaching why uncorrected gaps look smaller in that setting. Missing required electrolytes, non-finite values, out-of-range readings, and any negative sodium, chloride, bicarbonate, or albumin all fail with invalid_input and are not charged. Do not confuse this endpoint with osmolar gap calculators, strong ion difference tools, urine anion gap products, or full acid-base interpretation engines—those are different search intents and different contracts.

API usage, pricing, product workflows, and practical limits

Call the free in-browser anion gap calculator for classroom demos, nursing homework checks, and quick personal learning without reimplementing the formulas in every spreadsheet. Prefer consistent milliequivalent units for monovalent ions; if your UI only collects whole numbers, send integers and the engine still accepts numeric strings. Keep expectations educational: this is a calculation and learning tool, not a diagnostic medical device, and people with symptoms, known acid-base disorders, kidney disease, or medication changes should follow professional medical advice rather than any single automated number alone. Send a JSON body with required sodium, chloride, and bicarbonate values and optional albumin and normal_albumin when you want an explicit albumin correction. Use the prepaid API when a health SaaS, electronic worksheet, simulation lab, tutoring platform, or school LMS needs a stable contract under KIT balance at $0.002 per successful item; validation failures never consume balance after the engine rejects the request. Pair this endpoint with your own laboratory units and clinical workflow—confirm analyser methods for chloride and how your lab reports total carbon dioxide versus bicarbonate—then store both gaps alongside the raw electrolytes for dashboards and export columns for sodium, chloride, bicarbonate, albumin, anion_gap, and anion_gap_corrected. Authors shipping SDKs can map anion_gap and anion_gap_corrected into tables, colour bands for educational thresholds you define yourself, and step-by-step teaching cards that show the formula string.