Intestinal absorption of aluminium.

The intestinal absorption of aluminium can contribute significantly to systemic exposure to this element. Aluminium can be absorbed not only from oral pharmaceuticals but also from solid food and drinking water. The absorption process is not restricted to patients with kidney disorders; other groups of patients and healthy subjects are not excluded. Details of the absorptive mechanism are mainly obtained from in vitro (everted gut sac) and animal studies (intestinal perfusion) rather than from controlled human studies and case reports. The process of absorption depends on the intraluminal speciation, the intraluminal quantity, the presence of competing (iron, calcium) or complexing (citrate) substances and the intraluminal pH. The condition of the exposed organism with respect to the gut also determines intestinal absorption (iron status, calcium [vitamin D, parathyroid hormone] status, age and kidney function). Various absorption sites and passage routes, both transcellular and paracellular, have been reported, each apparently related to a different aluminium species (hydrated ionic species, aluminium citrate complex etc.). No uniform mechanistic model allowing extrapolation to the clinical situation has yet emerged.