Assessment of exposure to parenteral and oral aluminum with and without citrate using a desferrioxamine test in rats.

The primary purpose of this study was to determine the relative usefulness of various measures to monitor body aluminum burden in weanling rats fed various amounts of aluminum (0.39 mumol Al/g diet for 29 days, approximately 40 mumol Al/g diet with or without citrate for 29 days and approximately 100 mumol Al/g diet with citrate for 12 or 29 days) or injected intraperitoneally with graded doses of aluminum (0.01, 4.6, 11.8, 23.5 or 94 mumol Al). Twenty-four hours prior to sacrifice, all rats were injected intraperitoneally with either desferrioxamine (75 mg DFO) or buffer. All seven indices of aluminum exposure monitored (i.e. tibia, liver, kidney and serum aluminum concentrations; changes in serum aluminum concentrations in response to DFO; urinary aluminum excretion with and without DFO treatment) were highly (P < 0.001) correlated to parenteral aluminum exposure. Five of these measures (i.e. tibia, liver and serum aluminum concentrations and urinary aluminum excretion with and without DFO treatment) were also highly (P < 0.001) correlated to oral aluminum loads. Changes induced by DFO were very small. Moreover, the 'DFO stimulated' serum and urine aluminum concentrations were not more correlated to the body load of aluminum, as indicated by tibia aluminum concentrations, than baseline values. Comparisons of aluminum exposure in tibias and sera of rats exposed to parenteral and oral aluminum indicated that only 0.01-0.04% of dietary aluminum was absorbed. Ingestion of citrate had small but significant effects on aluminum retention.