Use sodium and glucose results from the same blood draw to estimate glucose-corrected sodium. Compare the measured result with two correction methods and their limitations.
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How to use it
Enter measured sodium and glucose from the same blood draw. Sodium mmol/L and mEq/L are numerically identical. Select glucose mg/dL or mmol/L as printed by your laboratory. The conventional 1.6 factor is the default; select 2.4 to compare the alternative. Test date is optional.
Formula and worked example
Corrected Na (mmol/L) = measured Na + factor × max[0, (glucose in mg/dL − 100) ÷ 100]. With measured Na 130 mmol/L and glucose 500 mg/dL, the 1.6 method gives 136.4 mmol/L and the 2.4 method gives 139.6 mmol/L. Glucose entered in mmol/L is multiplied by 18.0182. At or below 100 mg/dL, this calculator adds no negative correction.
Meaning and limitations
High glucose can shift water out of cells and lower measured sodium. A corrected value is an estimate, not a new sodium measurement. The displayed 135–145 mmol/L is a common adult laboratory interval for context; use the reporting laboratory’s interval and the clinical picture. The conventional factor is 1.6, while Hillier and colleagues found 2.4 a better overall estimate in their study. A single factor may be less accurate at very high glucose.
Water loss, kidney function, infusions and other solutes also matter. Repeat measurement and clinical evaluation during changing glucose can be important. Do not use this calculated result alone to diagnose a sodium disorder or decide on fluids, insulin or sodium treatment. Seek urgent care for marked weakness, confusion, seizure, fainting or severe dehydration.
What to check next
Check test timing, glucose unit and the measured sodium value. Review trends, symptoms and hydration with a clinician. A difference between correction factors is a reason to consider uncertainty rather than treat one estimate as definitive.
Frequently asked questions
Does the result change if glucose is not high?
This calculator adds zero correction at glucose 100 mg/dL or below. It cannot assess other causes of an abnormal sodium result.
Is a corrected value in the reference interval reassuring?
Not by itself. Measured sodium, glucose, osmolality, symptoms and the pace of change all matter.
Questions for an appointment
- Which factor suits my glucose level and clinical situation?
- Should sodium be remeasured as glucose changes?
- Could water loss, kidney disease, medicines or infusions affect interpretation?
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Sources and update
- Merck Manual Professional: conventional 1.6 correction
- Hillier et al. (1999): 2.4 correction factor study
Sources reviewed September 30, 2026. General information, not a diagnosis or substitute for clinical care. No independent clinician review is claimed.