For educational use. This tool is intended for reference and education. All care decisions require a direct clinical assessment of the patient and independent verification of doses and values by the treating team. The calculation runs locally in your browser, no patient data is sent to any server.

Free Water Deficit

Estimates the free water required to correct hypernatraemia. Useful in children with diabetes insipidus after neurosurgery in the pituitary region. The correction rate should not exceed 0.5 mEq/L/hour, to avoid cerebral oedema.

1.3
L free water deficit
Replace slowly – max 0.5 mEq/L/hour
Source: Adrogué HJ, Madias NE. Hypernatremia. N Engl J Med 2000;342(20):1493–1499. PMID 10816188 · doi:10.1056/NEJM200005183422006
Formula: FWD (L) = TBW × ((Nacurrent / Natarget) − 1)