14 July 2006
Background/Aims: Patients severely dehydrated from diarrhea are at risk of developing hyperkalemia consequent to fluid therapy treatment. In parallel with the regulation of external potassium balance by the kidney and gastrointestinal tract, plasma potassium is rapidly regulated by redistribution of potassium between the extracellular and intracellular compartments. Erythrocytes contain ATPases that play a role in this potassium movement. In this study, erythrocyte ATPase effectiveness was evaluated in infants dehydrated from diarrhea and compared to that of healthy infants. Methods: Blood samples were collected from dehydrated and healthy infants. The activity of Na<sup>+</sup>,K<sup>+</sup>-ATPase and of an ouabain-insensitive K<sup>+</sup>-ATPase were assessed. Serum electrolytes and blood pH were also determined. Results: No hyperkalemia was found, even in dehydrated infants presenting with severe hyperchloremic metabolic acidosis. In the erythrocytes of dehydrated infants, Na<sup>+</sup>,K<sup>+</sup>-ATPase activity was increased correlating positively with the amount of sodium administered. High K<sup>+</sup>-ATPase activity in the erythrocytes correlated with low plasma potassium. The K<sup>+</sup>-ATPase activity correlated positively with the amount of potassium administered to dehydrated infants. Conclusion: These findings suggest that the erythrocytes Na<sup>+</sup>,K<sup>+</sup>-ATPase and K<sup>+</sup>-ATPase both protect against plasma potassium abnormalities in dehydrated infants. In such infants, the risk of hyperkalemia is probably low.