Metabolic alkalosis (MAL) develops with increased difference of strong ions (SID) and with decreased concentration of non-volatile weak acids, i.e., albumin and phosphates. SID represents the difference between the sum of (i) all strong, dissociated, chemically not reacting cations and (ii) all strong anions. The calculation is easy to do. For the development and maintenance of MAL status of renal handling with hydrogen carbonate ion is significant, which is reabsorbed in the proximal tubule and regenerated in the distal nephron. The causes of increased SID are as follows: concentrational alkalosis, the gain of sodium not accompanied by corresponding gain of chlorides and/or the loss of chlorides without corresponding loss of sodium. This last group of MAL causes is abundant and comprises states caused by loss of gastric juice or by surplus of mineralocorticoids, regardless whether primary or secondary hyperaldosteronism. Interesting group of MAL causes are renal tubulopathies, responsible for the antenatal Bartter’s syndrome, „classical“ Bartter’s syndrome and Gitelman’s syndrome. A similar picture, i.e., hypokalaemic MAL, is also found in pseudo-Bartter’s syndrome, developing in patients without tubulopathies, most frequently after abuse of diuretic agents or accompanying cyclic vomiting. While patients with alkalising tubulopathies don’t spare chlorides in urine, patients with pseudo-Bartter’s syndrome do so. The clinical picture of MAL is influenced by volume depletion or by the MAL causes (e.g., vomiting). There may be a neurological symptomatology and/or myocardial functional changes. The relations between potassium ion andMALare very complex. The development ofMALcauses the depletion ofK+, and on the contrary, the depletion of K+ maintains and worsens MAL. At the beginning of MAL treatment it is necessary to eliminate the causes of the state, to correct the volume depletion and to supply potasium and chloride ions. Acetazolamide, arginine hydrochloride and hydrochloric acid represent also today the option of treatment in situations where it is impossible to treat MAL only by infusions of saline and by potassium salts.

        Key words: metabolic alkalosis, acid-base status, Bartter’s syndrome, pseudo-Bartter’s syndrome.