Sodium Corrected for Hyperglycaemia

Formula

Corrected Na = measured Na + k x (glucose mg/dL - 100)/100, with k = 1.6 (Katz) or 2.4 (Hillier).

Limitations

• Neither factor is universally accepted; the clinical response should guide therapy. The correction applies to glucose above 100 mg/dL; at or below 100 mg/dL no correction is applied.
• Hillier 1999 found an average fall of 2.4 mmol/L per 100 mg/dL of glucose; the 1.6 factor fitted up to 400 mg/dL, and above 400 mg/dL a larger factor (4.0) fitted better.

References

1. Hyperglycemia-induced hyponatremia: calculation of expected serum sodium depression. Katz MA. N Engl J Med. 1973;289(16):843-844. PMID 4763428
2. Hyponatremia: evaluating the correction factor for hyperglycemia. Hillier TA, Abbott RD, Barrett EJ. Am J Med. 1999;106(4):399-403. PMID 10225241