Dysbalances of sodium and chloride ions (Na + , Cl – ) in serum cause disturbances of the acid-base status. Hypochloraemia with natraemia within reference limits causes metabolic alkalosis, and hyperchloraemia, under the same conditions, metabolic acidosis. Hyponatraemia accompanied by a corresponding decrease of Cl – leads to dilutional acidosis. Hypernatraemia accompanied by a corresponding increase of Cl – leads to concentrational alkalosis. In a hyponatraemic state it is difficult to determine, whether the decrease of Cl – is proportional, or more or less intensive, than the decrease of natraemia. In the last two situations dil utional acidosis is combined with hypochloraemic alkalosis, or with hyperchloraemic acidosis respectively. Conversely, in states of hypernat - raemia a more intensive increase ofCl – leads to a mixed disturbance, concentrational alkalosis and hyperchlora- emic acidosis; a less intensive increase of Cl – leads to a mixed disturbance, concentrational alkalosis and hypochloraemic alkalosis. Instead of calculations, the authors present a graph, enab ling to determine easily the type of dysbalance between the two ions. The prompt and exact diagnosis makes the necessary treatment possible.

        Key words: acid-base status, sodium ion, chloride ion, dilutional acidosis, concentrational alkalosis, hypochlo- raemic alkalosis, hyperchloraemic acidosis.