Samples of serum and biliary drainage were obtained from biliary surgical patients and patients who did not undergo operation to assess the magnitude of magnesium loss and to determine whether serum and biliary magnesium concentrations differed with increasing levels of jaundice. Magnesium concentrations in biliary drainage varied more and were slightly lower than serum magnesium concentrations.
Only in the icteric group of patients was the difference between serum and biliary drainage magnesium concentration significant (P<.001). Depleted body stores of magnesium not reflected in the serum values of these patients and active uptake of the ion by the hepatobiliary system may account for the lower bile magnesium concentration found in this group.
In the absence of large volumes or prolonged courses of external biliary drainage, magnesium losses in bile would not seem to be a serious source of hypomagnesemia in the postoperative patient.