Sodium Correction Calculator

Sodium Correction Calculator for Nephrology. A corrected sodium that lands in the normal or high range means the measured hyponatremia is dilutional and will self-correct as glucose falls, so aggressive sodium repletion is unnecessary and a high corrected value flags a large free-water deficit. A corrected sodium that remains low points to genuine hypotonic hyponatremia coexisting with the hyperglycemia, which needs its own workup and management. Watch the corrected value rise as glucose drops during therapy; if measured sodium does not climb by roughly 2.4 mEq/L per 100 mg/dL fall in glucose, effective osmolality may be dropping and cerebral edema risk (particularly in children with DKA) increases. The Hillier factor of 2.4 is generally preferred and the nonlinearity is most pronounced above 400 mg/dL, where a factor closer to 4.0 fit the experimental data better.

How this calculator works

This tool estimates what the serum sodium would be if the plasma glucose were normal, correcting for the dilutional pseudo-hyponatremia that hyperglycemia produces as glucose osmotically pulls water from cells into plasma. Corrected Na = measured Na + [correction factor x (glucose - 100)/100], with glucose in mg/dL. Two factors are offered: the classic Katz value of 1.6 mEq/L per 100 mg/dL and the empirically derived Hillier value of 2.4 mEq/L per 100 mg/dL. It is arithmetic, not a validated risk score, so it carries no probability output.

When to use this calculator

Use whenever a patient with marked hyperglycemia (typically glucose above roughly 200 mg/dL, and especially in DKA or hyperosmolar hyperglycemic state) has a low or borderline measured sodium, to decide whether true sodium depletion exists and to guide fluid selection. The corrected value, not the measured value, should track the trajectory during insulin and fluid therapy. Do not apply it when glucose is near normal, and do not use it to estimate osmolality or free-water deficit directly; it addresses only the glucose contribution to measured sodium.

Inputs used

  • Measured sodium
  • Glucose

Clinical interpretation

A corrected sodium that lands in the normal or high range means the measured hyponatremia is dilutional and will self-correct as glucose falls, so aggressive sodium repletion is unnecessary and a high corrected value flags a large free-water deficit. A corrected sodium that remains low points to genuine hypotonic hyponatremia coexisting with the hyperglycemia, which needs its own workup and management. Watch the corrected value rise as glucose drops during therapy; if measured sodium does not climb by roughly 2.4 mEq/L per 100 mg/dL fall in glucose, effective osmolality may be dropping and cerebral edema risk (particularly in children with DKA) increases. The Hillier factor of 2.4 is generally preferred and the nonlinearity is most pronounced above 400 mg/dL, where a factor closer to 4.0 fit the experimental data better.

Worked example

A DKA patient has measured Na 128 mEq/L and glucose 700 mg/dL. Glucose excess = (700 - 100)/100 = 6 units of 100 mg/dL. Using Katz 1.6: corrected Na = 128 + (1.6 x 6) = 128 + 9.6 = 137.6 mEq/L. Using Hillier 2.4: corrected Na = 128 + (2.4 x 6) = 128 + 14.4 = 142.4 mEq/L. So the measured hyponatremia is entirely explained by hyperglycemia; the true sodium is normal-to-high, signaling substantial free-water deficit and arguing against interpreting 128 as sodium depletion.

Limitations and safety notes

The 1.6 factor comes from a small theoretical model and the 2.4 factor from a somatostatin-clamp study in only 6 healthy volunteers, so neither is validated in critically ill or DKA populations, and the true relationship is nonlinear above 400 mg/dL where both factors underestimate the shift. It does not detect or correct for true pseudohyponatremia from severe hyperlipidemia or hyperproteinemia (a laboratory artifact requiring direct-ISE measurement, a different problem). It assumes the measured glucose is acute and osmotically active, and it says nothing about tonicity contributions from mannitol, ethanol, or other osmoles.

Frequently asked questions

Should I use the 1.6 or the 2.4 correction factor?

The Hillier 2.4 factor is the better overall empirical estimate and is increasingly preferred; the traditional 1.6 works reasonably well up to a glucose of about 400 mg/dL but underestimates the true shift above that, where a factor near 4.0 fit the experimental data. Many clinicians report both. What matters most is applying one factor consistently while tracking the trend.

Why does the corrected sodium look higher than the measured value?

Excess glucose is osmotically active and draws intracellular water into the plasma, diluting sodium. Removing that dilutional effect reveals the underlying sodium, which is why the corrected number is higher. A high corrected sodium signals a significant free-water deficit that fluid therapy must address.

Does correcting the sodium change my fluid choice in DKA?

Yes, indirectly. A normal or high corrected sodium supports using more hypotonic fluid (for example 0.45% saline) after initial resuscitation, whereas a low corrected sodium favors staying with isotonic saline. Always interpret alongside volume status, potassium, and osmolality rather than in isolation.

Can I use this formula when glucose is only mildly elevated?

There is little point below roughly 200 mg/dL, where the correction is a fraction of a mEq/L and within lab noise. The formula matters most in severe hyperglycemia, DKA, and hyperosmolar hyperglycemic state, where glucose is high enough to meaningfully distort measured sodium.

Does this fix pseudohyponatremia from high lipids or protein?

No. That is a separate laboratory artifact of indirect ion-selective electrode or flame photometry measurement in samples with very high triglycerides or paraproteins, and it is resolved by direct-ISE measurement, not by this glucose correction.

References

  • Katz MA. Hyperglycemia-induced hyponatremia--calculation of expected serum sodium depression. N Engl J Med. 1973;289(16):843-4. PMID: 4763428.
  • Hillier TA, Abbott RD, Barrett EJ. Hyponatremia: evaluating the correction factor for hyperglycemia. Am J Med. 1999;106(4):399-403. PMID: 10225241.

Editorial review and citation methodology

Reviewed by the Quick Medical Calculator Editorial Team. Last reviewed: March 16, 2026. The review checks calculator inputs, intended population, interpretation, limitations, and source alignment.

  • Prefer original validation studies for scoring systems and prediction tools.
  • Use current specialty society guidance, transplant allocation policy, public health guidance, or regulator resources when they govern clinical use.
  • Include limitations and safety notes when a calculator is population-specific, context-dependent, or unsuitable as a standalone decision tool.

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