Sodium Correction for Hyperglycemia Calculator
Correct measured serum sodium for high glucose using the Katz factor: corrected Na = Na + 1.6 × ((glucose − 100) / 100), in mg/dL.
How to use this tool
- Enter the measured serum sodium in mmol/L.
- Enter the blood glucose in mg/dL.
- Read the glucose-corrected sodium value.
- Compare it with the reference note shown.
The sodium correction for hyperglycemia calculator estimates true serum sodium when high glucose has diluted it, using the standard Katz 1.6 correction factor.
Formula
Corrected Na = measured Na + 1.6 × ((glucose − 100) ÷ 100)
Glucose is in mg/dL and 100 mg/dL is the assumed baseline. Each 100 mg/dL rise in glucose above 100 adds about 1.6 mmol/L to sodium (the Katz factor).
How it works
High blood glucose pulls water out of cells into the bloodstream, diluting sodium and producing a falsely low measured value (dilutional or 'pseudo'-hyponatremia). Correcting sodium estimates what it would be once the glucose is normalised. The classic Katz factor adds 1.6 mmol/L of sodium for every 100 mg/dL that glucose exceeds 100 mg/dL.
The 1.6 factor is the traditional figure; some studies suggest a larger correction (around 2.4) at very high glucose levels. This calculator uses US conventional glucose units (mg/dL) and the standard 1.6 factor, and it assumes the low sodium is driven by hyperglycemia rather than another cause. Treatment decisions require clinical assessment.
This calculator is provided for general information and education only and is not medical advice. Clinical formulas are screening and estimation tools, not diagnoses, and they assume valid, correctly-measured inputs. Always consult a qualified clinician before making any decision about your health.
Worked example
Sodium 130 mmol/L with glucose 400 mg/dL
- Glucose excess = 400 − 100 = 300 mg/dL
- Divide by 100: 300 ÷ 100 = 3
- Multiply by 1.6: 1.6 × 3 = 4.8 mmol/L
- Add to measured sodium: 130 + 4.8 = 134.8 mmol/L
Corrected Sodium = 134.80 mmol/L (Corrected sodium still low)
Sodium correction for a measured Na of 130 mmol/L
| Glucose (mg/dL) | Correction (mmol/L) | Corrected Na |
|---|---|---|
| 200 | 1.60 | 131.60 |
| 300 | 3.20 | 133.20 |
| 400 | 4.80 | 134.80 |
| 600 | 8.00 | 138.00 |
| 800 | 11.20 | 141.20 |
Key terms
- Corrected sodium
- Measured sodium adjusted upward to estimate its value after high glucose is corrected, revealing true sodium status.
- Hyperglycemia
- Abnormally high blood glucose, which osmotically dilutes serum sodium.
- Katz factor
- The traditional correction of 1.6 mmol/L of sodium per 100 mg/dL of glucose above 100 mg/dL.
- Pseudohyponatremia
- A measured low sodium that is artifactual or dilutional rather than a true sodium deficit.
Frequently asked questions
- Why does high glucose lower measured sodium?
- Glucose is osmotically active and draws water out of cells into the blood, diluting sodium. Correcting for glucose estimates the sodium that would remain once glucose normalises.
- Should I use the 1.6 or 2.4 correction factor?
- 1.6 is the traditional Katz factor used here. Some evidence supports a larger factor (about 2.4) at very high glucose, so the corrected value is an approximation.
- What units does this use?
- Glucose is entered in mg/dL (US conventional units) and sodium in mmol/L (equivalent to mEq/L), with a baseline glucose of 100 mg/dL.