Increasing the accumulation of aluminum in the bone (body) in cases of renal osteodystrophy may influence the histopathologic aspect of the bones. Alumi- num blunts the effect of increased PTH secretion and favours the genesis of osteoid. That means, in cases of renal failure combined with aluminum accumulation, a relatively low bone tunover is found and no fibrosis of the bone marrow. Furthermore the amount of osteoid is increased. This means that there is evidence of osteomalacia especially when the latter is defined as an increased amount of osteoid covered with a relatively low number of cubic osteoblasts. To a certain extent the effect of aluminum accumulation is comparable to the effect of PTX. Treatment with DFO may normalize the bone, although not necessarily with a concomittant disappearance of alumi- num from the bone. The presence of aluminum in the bone can be suggested by routine histologic investigation of the bone and can be made rather probably by the aluminum staining combined with iron-staining, but can only be proven by more advanced techniques like ET AAS and LAMMA. References 1. Boyce BF, Elder HY, Elliot HL, Fogelman I, Gell GS, lunor Bl, Beastall G, Boyle YT, 1982: Hypercaicaemic ostemalacia due to aluminium toxicity. Lancet 6: 1009. 2. Verbueken AH, Visser Wl, Van de Vyver FL, Van Grieken RE, De Broe ME, 1986: The use of laser microprobe mass analysis (LAMMA) to control the staining of aluminum by aurin tricarboxylate (aluminon). Stain Technology 61: 287.