Stewart SID / strong ion gap (SIG)
Stewart SID / strong ion gap (SIG) - a deterministic tool in Sophie Well's Clinical Math & Conversions group.
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What this is
Stewart SID / strong ion gap (SIG) is one of 230 deterministic tools in Sophie Well's Clinical Math & Conversions group. Stewart SID / strong ion gap (SIG) - a deterministic tool in Sophie Well's Clinical Math & Conversions group.
When to use it
Use this tool when you need a quick, citable reference. Every calculation runs entirely in your browser - no inputs leave your device, no account is required, no AI is involved. The site enforces a strict Content Security Policy and ships no analytics or third-party CDN.
References
Stewart PA. Modern quantitative acid-base chemistry. Can J Physiol Pharmacol. 1983;61(12):1444-1461; albumin/phosphate charge per Figge J, Mydosh T, Fencl V. J Lab Clin Med. 1992;120(5):713-719. Read the source ↗
Worked example: SIG 17.8 mEq/L (apparent SID 45.4, effective SID 27.6): above ~2 mEq/L, suggesting unmeasured strong anions (ketoacids, sulfate, citrate, salicylate).
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