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Corrected sodium for hyperglycemia

Serum sodium as reported by the lab. mEq/L and mmol/L are numerically identical (sodium is monovalent).

Serum glucose in mg/dL (accepts mmol/L, ×18). The correction applies only above the 100 mg/dL reference.

Independent clinical validation: pending

Two independent clinical validators will be named here once review is complete.

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How it is calculated

Corrected sodium estimates the serum sodium that would be present if glucose were normal (100 mg/dL). For every 100 mg/dL of glucose above 100, add a fixed amount to the measured sodium — 1.6 mEq/L for the Katz (1973) factor, 2.4 mEq/L for the Hillier (1999) factor. Corrected Na = measured Na + (factor ÷ 100) × (glucose − 100). No correction is applied when glucose is at or below 100 mg/dL. Glucose is taken in mg/dL (mmol/L is converted ×18); sodium is mEq/L (= mmol/L).

Limitations and notes

This is a corrected laboratory value, not an ordinal score, so it has no interpretation bands — read the corrected value against the ordinary serum-sodium reference frame (corrected-sodium.md §Interpretation). Both correction factors are ADULT-DERIVED: Katz (1973) is a theoretical osmotic derivation and Hillier (1999) was measured in only 6 healthy adults; neither factor was derived or validated in children, so applying 1.6/2.4 to pediatric patients (e.g. DKA) is an off-derivation extrapolation [NEEDS SOURCE: a pediatric-specific validation or pediatric DKA guideline endorsing a factor]. Hillier's data are non-linear: 1.6 fits adequately up to ~400 mg/dL and the true factor climbs toward ~4.0 above 400 mg/dL, so above 400 mg/dL the real corrected sodium may exceed even the Hillier (2.4) estimate. Units are the main hazard: glucose must be mg/dL for the 1.6/2.4 coefficients (mmol/L is converted ×18); sodium mEq/L = mmol/L (monovalent, no conversion). The input plausibility bounds (Na 90–180 mEq/L, glucose 0–2000 mg/dL) are data-entry sanity guards, not cited thresholds [NEEDS SOURCE: an authoritative pediatric reference-interval / critical-value source]. Not a clinical device: it aids interpretation of sodium during hyperglycemia and does not by itself indicate therapy.

Accepted input ranges

  • Measured serum sodium — 90–180 mEq/L
  • Serum glucose — 0–2000 mg/dL

References

  1. Katz MA. Hyperglycemia-induced hyponatremia — calculation of expected serum sodium depression. N Engl J Med. 1973;289(16):843–844.PMID 4763428DOI 10.1056/NEJM197310182891607
  2. Hillier TA, Abbott RD, Barrett EJ. Hyponatremia: evaluating the correction factor for hyperglycemia. Am J Med. 1999;106(4):399–403.PMID 10225241DOI 10.1016/S0002-9343(99)00055-8
  3. MDCalc / Scholastica. Sodium Correction for Hyperglycemia. Independent reproduction of both formulas (Katz +0.016·(glucose−100); Hillier +0.024·(glucose−100)) with the 100 mg/dL reference.Source

Version and changelog

v1.0.0 · Renal and metabolic

  • 2026-07-25 v1.0.0 — Initial release: corrected sodium for hyperglycemia with both published factors (Katz 1.6 and Hillier 2.4).

Important

For use by qualified health professionals as an informational and educational aid. It supports clinical judgment and does not replace it. Verify every result independently before making a clinical decision. This is not a medical device.