pH-Adjusted Potassium Calculator

Estimate corrected serum potassium using blood pH to better interpret potassium shifts in acidemia and related metabolic states.

Last updated on: March 30, 2026

Calculate pH-Adjusted Potassium

Enter serum potassium in mmol/L or mEq/L. For potassium, both units are numerically equivalent.
pH
Typical input range: 6.8 to 7.8. This calculator is mainly intended for acidemia.

Clinical Significance

Serum potassium may appear normal or elevated in acidemia because hydrogen ions shift into cells while potassium shifts out. This can mask a clinically important total-body potassium deficit.

This is especially relevant in diabetic ketoacidosis and other acidotic states, where serum potassium can fall rapidly after insulin therapy and correction of acidosis.

Formula and Example

This calculator applies the approximate relationship that serum potassium changes by about 0.6 mmol/L for each 0.1 unit change in pH from 7.4.

Formula used: Corrected K = Measured K - 0.6 × ((7.4 - pH) / 0.1). This estimate is interpretive only and should not replace serial electrolyte monitoring or clinical judgment.

Example: if measured potassium is 4.8 mmol/L and pH is 7.10, then corrected potassium = 3.0 mmol/L.

Reference Interpretation

Severe Hypokalemia: < 3.0 mmol/L. High risk of muscle weakness, arrhythmias, and urgent potassium replacement may be required depending on the clinical setting.
Hypokalemia: 3.0 - 3.4 mmol/L. Potassium is below normal and should be interpreted with the full clinical picture, medications, and acid-base status.
Normal Range: 3.5 - 5.0 mmol/L. This adjusted value falls within the usual reference interval, but ongoing monitoring may still be necessary in unstable patients.
Hyperkalemia: > 5.0 mmol/L. Evaluate urgently in the appropriate clinical context, especially if ECG changes, renal dysfunction, or severe acidosis are present.

Clinical Notes

This calculator is best used as an interpretive aid. In DKA and other acidotic states, total-body potassium depletion may exist even when measured potassium is normal or elevated.

  • Do not use this result as a substitute for serial potassium measurements.
  • Interpret alongside ECG findings, renal function, bicarbonate, anion gap, and clinical status.
  • Potassium may decrease quickly after insulin administration and correction of acidosis.
  • Use established treatment protocols for DKA, hyperkalemia, or hypokalemia management.

This page has been medically reviewed by Dr. Khoulah Attia – PharmD, Immunology Specialist.

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