Potassium Deficit Calculator

Estimate the potassium deficit based on serum levels to guide replacement therapy.

Enter Values

Weight (kg)

Current Potassium (mEq/L)

Target Potassium (mEq/L)

Enter values above and click Calculate to see your result.

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(Target K - Current K) * Weight * 0.4

Approximates the total body potassium deficit. Note: Most potassium is intracellular, so serum levels only reflect a fraction of total stores.

70kg Patient, 3.0 K, Target 4.0 -> ~28 mEq deficit (Rule of thumb used clinically is often more aggressive).

Generally, 10 mEq of potassium raises the serum level by about 0.1 mEq/L, assuming normal renal function.

Potassium levels are difficult to correct if magnesium is low, because magnesium is required for the kidneys to retain potassium.

Serum potassium is only a small fraction of total body potassium (which is mostly inside cells), so it is an estimation of total stores.

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Corrected calcium for hypoalbuminemia.

Serum anion gap for metabolic acidosis.

CrCl for kidney function and drug dosing.

IV flow rate in gtt/min.

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