Effect of hyperosmolality and cations on iodinated contrast medium-induced potassium release from human blood cells

Potassium release from blood cells is a contrast medium-induced phenomenon. The purposes of the study were to (1) assess the effect of hyperosmolality and of adding sodium ions and calcium ions to a solution on potassium release from human blood cells and (2) reevaluate the possibility of hemolysis as a cause of potassium elevation.

Fresh human blood was mixed with a test solution to examine the temporal changes in the whole blood potassium levels and to calculate the potassium release rate. Test solutions included 5%, 20%, and 50% glucose; 0.9% and 10% NaCl; and 50% glucose mixed with various amounts of sodium and calcium ions. We also measured serum glutamine oxaloacetic acid transaminase (GOT) and serum lactate dehydrogenase (LDH) to evaluate the possibility of hemolysis.

Hyperosmolality using glucose solutions promoted higher potassium release. The average +/- SD potassium release rates were 7.3 +/- 2.4 micromol/min with 5% glucose, 13.5 +/- 2.3 micromol/min with 20% glucose, and 128.4 +/- 44.9 micromol/min with 50% glucose. The solutions including sodium ions showed lower release rates. The addition of sodium and calcium ions into 50% glucose significantly lowered the potassium release rates. No significant elevation of GOT or LDH was observed, and the possibility of hemolysis was eliminated.

Hyperosmolar glucose solution promoted potassium release, but the presence of sodium ions in the hypertonic solution inhibited it. In addition, there is no possibility of hemolysis as a cause of potassium release.