relationship between hydrogen ion concentration

Last reviewed 07/2021

There is a relationship between the extracellular concentrations of hydrogen and potassium because both compete with each other in the exchange with sodium which occurs across most cell membranes (in this instance an ion is pumped into the cell as sodium is pumped out) and in the distal tubule of the kidney (ion pumped into urine and sodium ion absorbed from the urine).

When acidaemia, i.e. high hydrogen ion concentration in the extracellular fluid, there is reduced exchange of potassium across cell membranes and less potassium lost in the urine because of the competition at these sites provided by hydrogen ions. Thus, in the acidotic patient there is a pseudo-hyperkalaemic state that may not reflect the total body potassium. Conversely, in a alkalotic patient, the reverse is true.