Sodium Correction for Hyperglycemia

What this tool does

Hyperglycemia draws water into the vascular space and can lower measured sodium. A simple linear correction estimates “effective” sodium for teaching and trend context; it is not a substitute for osmolality assessment or specialist care.

Formula (this page)

Na_corrected = Na_measured + 0.016 × max(0, glucose − 100) [glucose in mg/dL]

Equivalent to adding 1.6 mEq/L per 100 mg/dL glucose above 100. Some sources recommend different slopes (e.g., 2.4); compare with your local reference.

References

Katz MA. Hyperglycemia-induced hyponatremia—calculation of expected serum sodium depression. N Engl J Med. 1973;289(16):843-844.

Limitations

• Not validated for all populations; does not replace direct osmolality or expert management of DKA/HHS.
• Rapidly changing glucose and renal handling limit bedside interpretation from a single pair of values.

Hyperglycemia & osmolar state (teaching)

• Corrected sodium is a teaching adjunct; effective osmolality and clinical volume status guide DKA/HHS therapy.
• Insulin and fluid protocols should follow institutional pathways with frequent lab reassessment.
• Do not use a single corrected value to justify rapid sodium correction—risk of osmotic demyelination remains a separate concern.

Glucose-related increment applied in this model: +__ADJ__ mEq/L (for teaching; other coefficients exist in literature).