UKMedCalc

For healthcare professionals. Educational tool only — not a medical device. Verify all results against the current BNF, NICE guidance and local policy, and apply clinical judgement.

ElectrolytesRenal

Sodium Correction Rate (Adrogué–Madias)

Predicts the change in serum sodium per litre of infusate and the infusion rate needed to achieve a safe correction target in hyponatraemia.

The original equations were derived using sex at birth

years

Used to estimate total body water (lower fraction in the elderly)

kg
mmol/L
mmol/L

Chronic hyponatraemia: generally ≤8–10 mmol/L per 24 h; use 4–6 in high-risk patients

Enter the required values to see the result.

Formula

ΔNaper litre=Nainfusate−NaserumTBW+1Rate=target riseΔNaper litre÷24  h\Delta \text{Na}_{\text{per litre}} = \frac{\text{Na}_{\text{infusate}} - \text{Na}_{\text{serum}}}{\text{TBW} + 1} \qquad \text{Rate} = \frac{\text{target rise}}{\Delta \text{Na}_{\text{per litre}}} \div 24 \; \text{h}

TBW = weight × 0.6 (adult men), 0.5 (adult women or elderly men), 0.45 (elderly women). The formula predicts the change from one litre of infusate and does not account for ongoing renal or extrarenal losses.

Caveats & limitations

  • A prediction only — recheck serum sodium every 2–4 h during active correction and adjust the rate to the measured response.
  • Does not account for ongoing losses, urine output, water intake or treatment of the underlying cause (e.g. stopping thiazides, fluid restriction in SIADH).
  • Overcorrection risk is highest when a water diuresis emerges (e.g. after volume repletion in hypovolaemic hyponatraemia).
  • Seek senior/specialist input for severe (<120 mmol/L) or symptomatic hyponatraemia.

Evidence & UK guidance

Primary evidence

  • Adrogué HJ, Madias NE. Hyponatremia. N Engl J Med. 2000;342(21):1581–1589.

    PubMedDOI

UK practice

UK practice follows Society for Endocrinology emergency guidance and local policies: for chronic hyponatraemia limit correction to ≤10 mmol/L in the first 24 h (≤8 mmol/L — some use 4–6 — in high-risk patients: alcoholism, malnutrition, hypokalaemia, advanced liver disease) to avoid osmotic demyelination. Severely symptomatic hyponatraemia is managed with bolus hypertonic saline per guideline protocols, not this rate calculation.

Official resources

Formula and citations last verified: 2026-08-03

Related calculators

GIR

Calculates the glucose infusion rate in mg/kg/min from dextrose concentration and infusion rate — a core neonatal/paediatric TPN and fluid calculation.

CKD-EPI 2021 eGFR

Estimates GFR using the 2021 CKD-EPI creatinine equation, refitted without a race coefficient (ASN/NKF recommendation in the US).