- why do alterations in hydrogen Ion concentration occur in body fluids? - what problems can they cause? - what are the possible alterations for the concentration of sodium, Potassium, calcium and magnesium IONS in the Blood? - how much can they put the patient’s life at risk? These questions are answer in a simple and clear and intuitive way by “water and Salt”, a text that aims to provide a clinical interpretation method updated on the alterations of the acid-base balance, on hypo and hyper-natremia, on hypo and hypo-hyperkalemia (besides that of hypo and hyper-calcemia and hypo-magnesemia). the Reader is accompanied in the interpretation of the various alterations of the acid-base balance, by the many clinical cases proposed, the true strength of the text. The authors propose not only an interpretative path, but also clear and concise indications on the therapeutic behavior to be adopted for the management of acid-base balance disorders and of hydro-electrolytic alterations. The structure - first part: dedicated to the topic of acid-base balance. Through clinical cases the Reader is offered a correct interpretation of the most diverse alterations of the acid-base balance. Therapeutic indications are also included; - second part: dedicated to water and sodium. A physiological and pathophysiological analysis of water and sodium alterations is proposed. The treatment of hypo and hyper-natremia is the core of this section, Again thanks to the use of numerous clinical cases; - third part: dedicated to the alterations in the concentration of Potassium (hypo and hyper-kalemia), calcium (hypo and hyper-calcemia) and magnesium (hypo-magnesemia). the core of the chapter is made up of hypo and hyperkalemia.