Corrected Sodium for Hyperglycaemia Calculator

How it works

Corrected Na = measured Na + 1.6 × (glucose mg/dL − 100) / 100 (Katz); Hillier uses 2.4 instead of 1.6, better validated above 400 mg/dL

Glucose that cannot enter cells (as in insulin deficiency) stays in the extracellular fluid and pulls water out of cells by osmosis, diluting the sodium. The measured sodium in diabetic ketoacidosis therefore understates the patient’s true water deficit. Katz’s 1973 estimate — sodium falls 1.6 mmol/L for every 100 mg/dL (5.6 mmol/L) of glucose above normal — is the traditional correction; Hillier’s 1999 experimental data suggested 2.4 is more accurate, particularly when glucose exceeds 400 mg/dL. The corrected sodium tells you what the sodium will do as insulin brings glucose down: a normal or high corrected value means the patient is actually hypernatraemic and dehydrated and will need free water, while a still-low corrected value indicates genuine hyponatraemia.

Worked example

Sodium 131 with glucose 32 mmol/L (576 mg/dL): excess 476 mg/dL → Katz 131 + 7.6 = 138.6; Hillier 131 + 11.4 = 142.4 — the hyponatraemia is dilutional.

Frequently asked questions