[Changes in magnesium levels in surgery of the digestive tract]

We studied serum concentrations of magnesium post-operatively in 41 patients divided up into four distinct groups, depending on the degree of seriousness of the operation, the loss of body fluids and the duration of intravenous feeding. The results thus obtained showed us that in digestive disorders there is an initial fall in blood magnesium accentuated in operated patients submitted to continous gastric aspiration or an external biliary drain. In these same patients, there is a tendency to normalisation from the second day after the operation. Only patients with gastric or intestinal fistulas had a curve which fell to the seventh post-operative day reaching severe levels of hypomagnesemia.