[Aluminum absorption in the presence of normal kidney function: the effect of the pH]

Aluminium is a toxic metal of known importance in patients with chronic renal failure on hemodialysis, with a gastrointestinal absorption modulated by several factors including gastric pH which modifies the solubility of Aluminium hydroxide and can increase its absorption. We studied twenty six patients with normal renal function: control (n = 13); presurgery (n = 8); postsurgery (n = 5) by an aluminium hydroxide absorption test (30 mg/kg); serum and urinary aluminium was determined as well as gastric pH and hematologic parameters at different time periods. It was observed that presurgery ulcer patients (pH mean = 2.09) increased serum and urine aluminium levels as well as aluminium/creatinine ratio in urine after the test, opposite to what occurs in the postsurgery group (pH mean = 5.78) in which such parameters were not significantly modified. No differences were found in hematological parameters between the two groups. Our results indicate that acid gastric pH seems to be a factor capable of increasing gastrointestinal absorption of aluminium hydroxide since its solubility and thus its disponibility is increased, and make a point on the risk of a prolonged administration of antacids containing aluminium in patients with normal renal function.