Corrected Sodium (for Hyperglycemia)
Adjusts measured sodium for the dilutional effect of hyperglycemia
Calculator
Why use it
Reveals true sodium status in hyperglycemic states (DKA, HHS). Prevents inappropriate treatment of pseudohyponatremia. Guides fluid selection (normal saline vs. half-normal saline) during DKA management.
About
Corrected sodium adjusts the measured serum sodium for the dilutional effect of hyperglycemia. Elevated blood glucose draws water into the intravascular space, diluting sodium. The corrected value reveals the true sodium status once glucose normalizes, which is critical in managing DKA and HHS.
When to use
- DKA or HHS with hyperglycemia and hyponatremia
- Any hyperglycemic patient with low measured sodium
- Monitoring sodium trends during DKA/HHS treatment
Formula
Pearls & pitfalls
- Classic Katz correction: Na increases by 1.6 mEq/L for every 100 mg/dL glucose above 100.
- Hillier revision: 2.4 mEq/L correction per 100 mg/dL may be more accurate at very high glucose (> 400).
- As glucose drops during treatment, measured Na should rise — if it does not, suspect free water excess.
- This correction applies ONLY to hyperglycemia — not to other causes of pseudohyponatremia (lipemia, paraproteinemia).
- Use the corrected sodium to guide fluid decisions in DKA, not the measured value.
Next steps
If corrected Na > 145: Use hypotonic fluids (0.45% NS) after initial resuscitation. If corrected Na < 135: True hyponatremia exists alongside hyperglycemia. Monitor corrected sodium as glucose normalizes.
Evidence
Original correction factor of 1.6 mEq/L per 100 mg/dL by Katz (1973). Hillier et al. (1999) proposed 2.4 mEq/L at glucose > 400 mg/dL based on experimental data. Both are commonly used; Katz remains the most widely referenced.