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Potassium Correction Based on Changes in pH


Corrected potassium based on pH


Background


The relationship between serum potassium levels and changes in blood pH varies widely depending on several factors.  Generally speaking, declines in pH leads to increases in serum potassium, while increases in pH leads to declining potassium levels.  Several sources promote the use of an older equation:

Old Rule of Thumb


K+ corrected = K+ level  -  [0.6 x (pH initial - pH current)/0.1]

K+ corrected: what the serum potassium would be in the absense of the acid-base disorder.

The equation above was considered a rough estimate and further studies found that there could be considerable variance between changes in blood pH and the final impact on serum potassium levels. For example, declines in pH from organic acidosis such as ketoacidosis (diabetes, starvation, ethanol) or  lactic acidosis (circulatory or respiratory failure, liver failure, sepsis, cancer, other) leads to little or no effect on potassium levels. Conversely, inorganic (mineral acidosis) from chronic renal failure for example can cause major shifts out of cells leading to significant increases in plasma potassium levels

 



Inputs:




Potassium level  mmol/L or  mEq/L


pH Initial

pH Final



Select any that apply



Organic acidosis present e.g. lactic acidosis or ketoacidosis?

 


Non-organic (mineral acidosis) present e.g. chronic renal failure, Type I (distal renal tubular acidosis), other





Respiratory or metabolic alkalosis present?

 

Respiratory acidosis present?


heart

 
 


References top of page

 

  1. Androgue HJ, Madias NE. Changes in plasma potassium concentration during acute acid-base disturbances. Am J Med 1981;71:456–67.
  2. Aronson PS, and Giebisch G. Effects of pH on Potassium: New Explanations for Old Observations. JASN November 2011, 22 (11) 1981-1989; DOI: https://doi.org/10.1681/ASN.2011040414
  3. Burnell JM, Scribner BH, Uyeno BT, Villamil MF. The effect in humans of extracellular pH change on the relationship between serum potassium concentration and intracellular potassium.  J Clin Invest. 1956;35(9):935.  https://pubmed.ncbi.nlm.nih.gov/13367188/
  4. Fulop M. Serum potassium in lactic and keto acidosis. N Engl J Med 1979; 300:1087–90.
  5. Rastergar A, Soleimani M. Hypokalaemia and hyperkalaemia. Postgrad Med J 2001;77:759–764.
Potassium Correction Based on Changes in pH