[Changes in the Na+, K+, and Ca++ concentrations in the urine in the course of surgical interventions]

The tests were carried out on 27 surgical patients. Diuresis and the Na, K and Ca concentrations in the urine were measured before, during and after operation. Due to operational stress and to the drugs used for general anaesthesia diuresis decreases progressively during operation and compared to the conscious state the amount of cations excreted during operations is significantly lower. Decrease of the serum potassium and calcium levels is not explained with the quantity of ions excreted with the urine.