Does aluminium have a pathogenic role in dialysis associated arthropathy?

Annals of the RHEUMATIC DISEASES Leader Does aluminium have a pathogenic role in dialysis associated arthropathy? Dialysis has improved the prognosis and quality of life for patients with chronic renal insufficiency, but at the price of various complications. The first to be recognised were the acute myoclonic encephalopathies,' 2 whose main cause is aluminium overload. This overload results from the use of phosphate binding gels containing aluminium to lower the hyperphosphataemia of these patients, and also from dialysis solutions with a high aluminium content. The incidence of this syndrome has decreased dramatically since the lowering of aluminium concentrations in dialysis solutions and the monitoring of plasma aluminium concentrations in these patients. Nevertheless, some patients still have altered cerebral function related to moderate aluminium overload.3 Other complications can arise in patients receiving long term dialysis,4 5 including hypochromic anaemia6 and osteomalacia.7 The common factor in these complications is the toxicity of aluminium to the organs and tissues affected. Thus aluminium can induce encephalopathies in rats,8 and its tropism for the grey matter of the central nervous system in man has been shown.' Similarly, this element can inhibit bone mineralisation9; it is toxic to osteoblasts and accumulates at the mineralisation front of bone in patients undergoing dialysis.5 9 Indirect evidence of the toxicity of aluminium is the improvement in neurological, haemato-logical, and bony disorders produced by the chelator desferrioxamine. In particular this chelator enhances the activity oferythrocyte (and probably brain) dihydropteridine reductase, and improves the psychomotor function of the patient receiving long term haemodialysis.3 Dialysis associated arthropathy Certain osteoarticular complications of long term haemo-dialysis were recognised early. 1'12 These include epiphysial necrosis, septic or microcrystalline arthritis, lesions of hyperparathyroidism, and tendon ruptures. The increased survival times of patients undergoing haemodialysis have more recently shown a set of manifestations'-'8 described under the term 'dialysis associated arthropathy'. This crippling disorder affects a large number of patients after 10 years of haemodialysis. It is expressed clinically by carpal tunnel syndrome, often bilateral and recurrent, or destructive arthropathies affecting the spine and limbs. Radiographs typically show erosive spondyloarthropathy and juxta-articular cystic lesions of the limbs, predominantly in the wrists, shoulders, knees, and hips. The histological aspects are highly polymorphous, varying with the joint and the patient, so that division of dialysis associated arthropathy into several subgroups has been suggested.'7 Nevertheless, a particular amyloidosis consisting of 02 microglobulin amyloid'9 20 iS often involved in compression of the …