Aluminium and uremic bone disease. Usefulness of serum aluminium level anddeferoxamine (DFO) test

The optimal control of aluminium content in dialysis fluids has resulted in a decrease in the incidende of aluminium related bone disease (ARBD) and i n the risk fbr aluminium toxicity. Nevertheless the problem has not disappe ared. Bone biopsy with specific staining for Al remains the only reliable m ethod for the diagnosis of ARBD. Currently there is not a total agreement o n the reliability of serum Al levels and of the DFO test in the identificat ion of patients with Al overload or toxicity In a series of patients (mean age 48 +/- 14 years old) from our hemodialysi s units Lye carried out bone biopsy and we studied the prevalence of bone a luminium overload and of ARBD and the usefulness of serum aluminium and of DFO test in their diagnosis. Seventy three bone biopsies were evaluated by histomorphometric analysis an d aluminium staining (Aluminon). Al overload was diagnosed when the Alumino n staining was positive independent of the Done surface covered with Al and of the bone formation rate (BFR). Patients were considerer to have ARBD wh en aluminium covered > 25% or bone surface and BFR was < 0,031 mum(3)/mum(2 )/day. Fifteen patients had aluminium overload while 7 patients were consid ered to have ARBD. Positive Aluminon staining appeared in all histopatholog ical forms of renal osteodystrophy although it appeared mainly in patients with mixed lesion and osteomalacia. Most of the patients with adynamic bone disease had negative Aluminon staining. Patients with aluminium overload s howed lower bone formation and mineralization rates. Serum aluminium levels below 40 mug/l were useful to exclude bone aluminium overload. Serum aluminium levels and DFO test were not specific in diagnos ing aluminium overload or ARBD. A DFO test with an increment in serum alumi nium over 100 mug/l in combination with a serum PTH below 200 pg/ml was use ful to diagnose ARBD.