Sodium Correction Calculator — Hyperglycaemia Correction
High blood glucose draws water out of cells into the bloodstream by osmosis, diluting the serum sodium — a phenomenon called translocational hyponatraemia. This calculator corrects the measured sodium for glucose elevation using both the Katz (1.6 mEq/L per 100 mg/dL) and Hillier (2.4 mEq/L per 100 mg/dL) formulas, revealing the true underlying sodium level.
mEq/L
Glucose unit
True hyponatraemia present even after glucose correction
- 1
Glucose excess above normal
400 − 100 = 300Only glucose above 100 mg/dL dilutes serum sodium. - 2
Per-100 correction factor
300 ÷ 100 = 3 - 3
Katz correction (×1.6)
1.6 × 3 = 4.8 - 4
Corrected sodium (Katz)
130 + 4.8 = 134.8
How does this calculator work?
Corrected Na = Measured Na + 1.6 × [(glucose − 100) / 100] using Katz (1973), or + 2.4 × [(glucose − 100) / 100] using Hillier (1999), where glucose is in mg/dL. High glucose draws water into plasma and dilutes sodium; the correction reveals the true sodium. If corrected Na is still below 135, true hyponatraemia exists and warrants separate workup.
Formula
How this is calculated
Glucose is an osmotically active solute. When blood glucose rises sharply — for example in diabetic ketoacidosis (DKA) or hyperglycaemic hyperosmolar state (HHS) — it raises plasma osmolality and draws intracellular water into the vascular space. This dilutes the sodium, causing the measured sodium to appear low even when total-body sodium is normal or even elevated. This is called translocational (or redistributional) hyponatraemia and should be distinguished from true hyponatraemia before deciding on treatment.
The Katz correction (1973) adds 1.6 mEq/L to the measured sodium for every 100 mg/dL that plasma glucose exceeds 100 mg/dL. This is the traditionally taught formula and is widely used in emergency and internal medicine. The Hillier formula (1999) uses a factor of 2.4 mEq/L per 100 mg/dL instead, derived from a more physiologically realistic model that accounts for glucose-induced insulin suppression and is considered more accurate when glucose is very high (>400 mg/dL).
If the corrected sodium falls below 135 mEq/L, true hyponatraemia exists independently of the glucose effect and requires further investigation. If the corrected sodium is normal (135–145 mEq/L), the hyponatraemia was purely dilutional and will resolve as glucose is treated. The calculator is for educational and clinical reference only — always interpret results in the full clinical context.
Frequently asked questions
The Hillier factor of 2.4 mEq/L per 100 mg/dL is more accurate at very high glucose levels (above ~400 mg/dL), as it was derived from a model that better reflects the physiology of glucose-induced osmotic shifts. At moderate glucose levels, the difference between the two formulas is small. Many guidelines now recommend 2.4 as the default correction factor.
Yes. In DKA, if the corrected sodium is high or rising, it suggests the patient is significantly dehydrated and may need more fluid or a less hypertonic resuscitation fluid. A corrected sodium below 135 suggests true hyponatraemia co-existing with DKA, which requires separate investigation once the glucose-driven dilution is accounted for.
No. Pseudohyponatraemia (also called artefactual hyponatraemia) refers to falsely low sodium readings caused by very high triglycerides or paraproteinaemia displacing plasma water — it is a laboratory measurement artefact. Translocational hyponatraemia from hyperglycaemia is a real shift of water between compartments, not a measurement error. This calculator corrects for the latter.
Also known as
TG we-Calculate Editorial Team. (2026). Sodium Correction Calculator — Hyperglycaemia Correction [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/sodium-correction-calculator
TG we-Calculate Editorial Team. "Sodium Correction Calculator — Hyperglycaemia Correction." TG we-Calculate. 2026. https://we-calculate.com/calculator/sodium-correction-calculator.
TG we-Calculate Editorial Team, "Sodium Correction Calculator — Hyperglycaemia Correction," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/sodium-correction-calculator
@misc{wecalculate_sodium_correction_calculator, title = {Sodium Correction Calculator — Hyperglycaemia Correction}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/sodium-correction-calculator}}, year = {2026}, note = {TG we-Calculate} }
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