Ivica Lazúrová
The most important mechanisms regulating body fluid volume are thirst and antidiuretic hormone, i.e. ADH (arginin-vasopresin, AVP). These two mechanisms are mostly influenced by changes of plasma osmolality. However, ADH secretion can be modulated by nonosmotic changes, such as hypovolaemia, hypotension, nausea etc. Water metabolism disturbances are practically manifested as hypo - or hypernatremia. Hyponatraemia, depending on extracellular fluid volume, may be hypovolaemic, euvolaemic or hypervolaemic. Author discuss about diagnosis and management of these three types of hyponatraemia. Hypernatraemia is less common in clinical practice and usually indicates water deficiency. Author presents its causes, diagnosis and management.