Bismuth in human serum: reference interval and concentrations after intake of a therapeutic dose of colloidal bismuth subcitrate.

A sensitive method for the determination of the bismuth concentration in human serum is described. Analyses were carried out by inductively coupled plasma-mass spectrometry (ICP-MS), after a simple dilution of the samples with nitric acid. The detection limit of the applied method is 0.007 microgram/l whereas relative standard deviations varied from 5.7 to 13.6%. Determination of reference values in human serum of healthy adults gave a range from < 0.007 to 0.067 microgram/l (19 persons). Bismuth concentrations in serum were also measured before, during and after the intake of therapeutic doses of colloidal bismuth subcitrate (CBS). About 1.5-2 h after the intake of one tablet of CBS, the bismuth concentration in serum was found to have increased 51-1483 times (two apparently healthy volunteers and six hospitalized patients), showing that the serum bismuth concentrations can increase by several orders of magnitude during the intake of CBS. During the intake of four tablets of CBS per day by two apparently healthy volunteers, bismuth concentrations in serum after an overnight fast were found to be, respectively, 5.56 and 8.1 micrograms/l on day 15 and 4.28 and 13.6 micrograms/l on day 29. After stopping the therapy, the concentration of bismuth in serum slowly returned towards normal over a period of months.