Sodium Correction Calculator - Adrogué-Madias Rate and Safety

A sodium correction calculator is a clinical dosing tool that uses the Adrogué-Madias formula to plan a safe serum sodium correction in hypernatremia and hyponatremia. It takes sex, age group, body weight, current and target serum sodium, IV fluid, and planned time, then returns the ΔNa per liter, total volume, infusion rate, and 24-hour correction.

• • Pre-rounds chronic hyponatremia review: enter the basic metabolic panel, pick 0.9% NaCl, and see the planned hourly and 24-hour correction before orders.
• • Symptomatic severe hyponatremia bolus check: use 3% NaCl to see the expected rise from a 100 mL bolus, then recheck serum sodium at 1 to 2 hours.
• • Chronic hypernatremia free-water plan: pair D5W or half normal saline with the planned 24-hour correction to stay inside the 12 mEq/L ceiling.
• • Adrogué-Madias worked example: recheck the 70 kg adult male, serum Na 128 mEq/L, 0.9% NaCl, target 135 mEq/L, 24-hour plan.

The result is most useful when the basic metabolic panel and the IV fluid choice come from the same chart review. The default target sits inside the 135 to 145 mEq/L range.

According to MedlinePlus, the normal serum sodium range is about 135 to 145 mEq/L, and a value outside that range should be read alongside volume status.

The calculator is a planning tool, not a stand-alone diagnosis. Volume status, urine sodium, and serum osmolality still drive the final correction rate.

The companion Sodium Change Calculator corrects serum sodium for hypertriglyceridemia.

The sodium correction calculator applies the Adrogué-Madias formula in three steps, then converts the result into a volume, an infusion rate, and a 24-hour correction estimate. The same calculation drives the bedside correction plan for both hyponatremia and hypernatremia.

• [Na+]infusate: Sodium content of the chosen IV fluid: 154 for 0.9% NaCl, 513 for 3% NaCl, 77 for 0.45% NaCl, 130 for lactated Ringer's, 0 for D5W.
• [Na+]serum: Current serum sodium in mEq/L. Reference range 135 to 145 mEq/L.
• TBW: Total body water in liters, equal to body weight times a sex- and age-specific water fraction.
• Δ[Na+]: Expected change in serum sodium per liter of the chosen infusate.
• Infusion rate: Total infusate volume divided by the planned hours to target, in mL/hr.

The same formula is used in the Adrogué-Madias New England Journal papers on hyponatremia and hypernatremia, the Merck Manual chapter on hypernatremia, the AAFP 2015 hyponatremia review, and the Omni Calculator reference. The safety limits are 10 mEq/L per 24 hours for chronic hyponatremia, 0.5 mEq/L per hour for the chronic hyponatremia hourly rate, and 12 mEq/L per 24 hours for chronic hypernatremia.

The total volume and the infusion rate are derived outputs that fall out of the formula once the planned time is set.

According to Merck Manual, the Adrogué-Madias formula gives the expected change in serum sodium per liter of infusate, and chronic hypernatremia should be corrected by no more than about 12 mEq/L per 24 hours.

The same lab-to-clinical-number pattern shows up in Corrected Calcium Calculator, which uses the Payne rule for an albumin-adjusted calcium.

Four concepts drive every result the calculator returns.

Each concept is the same one a bedside clinician uses when planning a correction. The Adrogué-Madias formula is the engine, the TBW fraction is the scaling, the infusate sodium is the lever, and the chronic correction limits are the safety envelope.

Patients with cirrhosis, heart failure, chronic kidney disease, or a recent neurosurgical procedure need extra caution.

Most metabolic panels that trigger a sodium correction also report a bicarbonate, and Anion Gap Calculator translates that bicarbonate into a band on the same chart review.

The form is built for a small set of basic metabolic panel values and a single IV fluid choice.

1. 1 Pick sex and age group: the pair loads the published total body water fraction.
2. 2 Enter body weight: the calculator multiplies weight by the TBW fraction to estimate total body water.
3. 3 Enter current and target serum sodium: the default 140 mEq/L sits inside the 135 to 145 mEq/L range.
4. 4 Choose the IV fluid: 0.9% NaCl, 3% NaCl, 0.45% NaCl, lactated Ringer's, or D5W with the published sodium content preloaded.
5. 5 Enter the planned time to target: the default 24 hours matches the chronic envelope.
6. 6 Read the result and clinical guidance: the result panel shows the ΔNa per liter, total volume, infusion rate, hourly and 24-hour correction. Plans above the chronic ceiling are flagged.

A 70 kg adult male has a serum sodium of 128 mEq/L. Pick sex male, age group adult, weight 70, current Na 128, target Na 135, IV fluid 0.9% NaCl, planned 24 hours. The calculator returns ΔNa 0.60 mEq/L per L, total volume 11.58 L, infusion rate 482.4 mL/hr, 24-hour correction 7.0 mEq/L.

Volume status is the next thing to confirm before any sodium correction plan is ordered, and FENa Calculator classifies hyponatremia from the same panel.

Using a sodium correction calculator gives the bedside team a standardized plan in under a minute, with the same units on every chart review.

• • Standardized Adrogué-Madias math: returns the ΔNa per liter, total volume, infusion rate, and 24-hour correction with the same published units on every chart review.
• • Built-in chronic safety envelope: flags any plan that would cross the 10 mEq/L per 24 hours or 0.5 mEq/L per hour chronic hyponatremia limits, or the 12 mEq/L chronic hypernatremia limit.
• • Patient-specific total body water: loads the published TBW fraction from the sex and age group pair.
• • Five standard IV fluids covered: 0.9% NaCl, 3% NaCl, 0.45% NaCl, lactated Ringer's, and D5W with the published sodium content preloaded.
• • Symptomatic bolus planning: returns the expected rise from a 100 mL 3% saline bolus.
• • Shared language with the care team: hospitalists, nephrologists, endocrinologists, and pharmacists read the same mEq/L per liter, mL/hr, and mEq/L per 24 hours numbers.

The same calculator is used for chronic hyponatremia, chronic hypernatremia, and the symptomatic severe hyponatremia bolus workflow, which makes it a shared language across the care team.

The most useful pattern is to run the calculator before orders, recheck at 4 to 6 hours, and re-enter the new serum sodium.

Hypomagnesemia and hyponatremia often coexist in chronic alcohol use, malabsorption, and diuretic therapy, and Corrected Magnesium Calculator is the natural second step.

Five patient and lab variables can move the result by more than a full band. Each is a known source of error.

• • The Adrogué-Madias formula is a planning tool, not a stand-alone diagnosis. Volume status, urine sodium, and serum osmolality still drive the final correction rate.
• • Children, pregnant patients, and patients on chronic parenteral nutrition can have atypical total body water fractions, so the calculator should always be read alongside the clinical context.

The result is a planning estimate, so the next step is always a basic metabolic panel recheck at 4 to 6 hours.

Patients on vasopressin, thiazide diuretics, or with syndrome of inappropriate antidiuretic hormone secretion can have a paradoxical rise in serum sodium after the cause is removed.

According to AAFP, chronic hyponatremia is held to about 10 mEq/L per 24 hours or 0.5 mEq/L per hour, and a 100 mL bolus of 3% saline is used for symptomatic severe hyponatremia.

Kidney function changes both the chronic correction limit and the choice of IV fluid, and GFR Calculator is the natural read-along in chronic kidney disease.