Sodium Correction Calculator

Correct a measured serum sodium level for hyperglycemia using the Katz or Hillier factor, then see whether the adjusted value falls in the hyponatremia, normal, or hypernatremia range.

Quick Facts

Classic factor
1.6 mEq/L per 100 mg/dL
Katz (1973) correction factor, the traditional standard.
High-glucose factor
2.4 mEq/L per 100 mg/dL
Hillier et al. (1999) factor, often cited for markedly elevated glucose.
Normal sodium range
135-145 mEq/L
Reference range used to classify the corrected value.

Your Results

Calculated
Corrected sodium
-
Adjusted for hyperglycemia
Correction added
-
mEq/L added to measured value
Glucose excess
-
Above 100 mg/dL reference
Classification
-
Based on corrected sodium

Ready

Enter the measured sodium and glucose, then calculate the corrected sodium.

About the sodium correction calculator

Hyperglycemia pulls water out of cells and into the bloodstream by osmosis. That extra plasma water dilutes sodium, so a measured serum sodium can look low even when total body sodium is unchanged — a pattern often called translocational or dilutional hyponatremia. The sodium correction calculator backs that dilution effect out of the measured value to estimate what sodium would read if glucose were normal.

How the correction works

The standard formula is:

Corrected sodium = Measured sodium + factor × (Glucose − 100) / 100

Glucose is in mg/dL, and the factor is either 1.6 mEq/L per 100 mg/dL (the classic Katz, 1973, correction) or 2.4 mEq/L per 100 mg/dL (Hillier et al., 1999, an empirically derived alternative often cited as a closer fit at markedly elevated glucose). No correction is applied when glucose is at or below the 100 mg/dL reference point.

Interpreting the corrected value

Once corrected, compare the value against standard sodium bands: below 125 mEq/L is generally classed as severe hyponatremia, 125-129 moderate, 130-134 mild, 135-145 is the normal range, and above 145 is hypernatremia. A corrected value that lands in the normal range suggests the low measured sodium was largely explained by the glucose dilution effect; a corrected value that stays low suggests a true sodium deficit is also present.

When to consult a professional

This tool performs the corrected-sodium arithmetic for education and record-keeping. It is not a diagnosis and does not direct treatment. Any decision about fluids, insulin, or further testing should rest with a licensed healthcare provider who can weigh the whole clinical picture.

Frequently Asked Questions

What does a sodium correction calculator do?
It adjusts a measured serum sodium value to account for hyperglycemia. High glucose pulls water out of cells into the bloodstream by osmosis, which dilutes sodium and lowers the measured value even though total body sodium has not changed. The corrected sodium estimates what the sodium would read if glucose were normal.
How is corrected sodium calculated?
Corrected sodium equals measured sodium plus a factor times (glucose minus 100) divided by 100, where glucose is in mg/dL. The classic Katz (1973) factor is 1.6 mEq/L per 100 mg/dL of glucose above 100. The Hillier et al. (1999) factor is 2.4 mEq/L per 100 mg/dL, derived empirically and often cited as a better fit at higher glucose levels. No correction is applied when glucose is at or below 100 mg/dL.
Should I use the Katz or Hillier factor?
Katz (1.6) is the traditional, most widely cited factor and is reasonable across the typical range of hyperglycemia. Hillier (2.4) was derived from measured data and is sometimes preferred at markedly elevated glucose, such as in diabetic ketoacidosis or hyperosmolar states. Neither factor is a universal standard, so the correction should be read as an estimate, not an exact lab value.

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