Investigation of the aluminium biokinetics in humans: A ²⁶Al tracer study

Despite the well-known toxicity of aluminium in chronic renal failure, a solid database on its biokinetics has been difficult to establish. A highly sensitive method using ²⁶Al as tracer and accelerator mass spectrometry (AMS) for detection was used. No perturbing background and saturation effects were taken into account using a delta function input of aluminium in time. Aluminium absorption, distribution, speciation and excretion in six healthy volunteers and in two patients with chronic renal failure were investigated following administration of a single oral or i.v. dose of ²⁶Al. Serial samples of blood and urine were taken. In a speciation study, the time dependence of the binding of ²⁶Al to low-molecular weight molecules in serum was investigated. The measured data were compared and interpreted with simulations in an open compartmental model. Fractional absorption, distribution, excretion and time constants for the aluminium transport were determined. Typical intestinal absorption rates for AlCl ₃ were found to be in the range of 10^-3. The ultrafiltrable percentage of aluminium in serum of one volunteer was estimated to be 5.6±0.8%. Differences between healthy volunteers and patients with chronic renal failure were deduced. The employed method using ²⁶Al and ams has proven to be highly sensitive for investigations of aluminium biokinetics at the ultra-trace element level. With the model, the measured values of ²⁶Al in serum and urine were used to precisely determine absorption, speciation, distribution, retention and excretion of aluminium in humans.