Aluminium-related osteomalacia: response to reverse osmosis water treatment

It is generally accepted that aluminium induces osteomalacia in chronic hemodialysis patients by binding to the calcification front, thereby inhibiting mineralization of osteoid. Because this form of osteomalacia is vitamin D resistant, the condition has often been assumed to be irreversible, although promising results have been achieved recently by using a chelating agent for removal of aluminium from the skeleton. In this paper we present four chronic hemodialysis patients with aluminium toxicity and histologic osteomalacia in whom the mineralization defect greatly regressed after the use of reverse osmosis treated-water for dialysis, but without further treatment. In three other patients, also with aluminium toxicity and histologic osteomalacia, similarly treated, the histological severity of the osteomalacia remained static. Those patients in whom bone mineralization status improved developed hyperparathyroidism after reverse osmosis water-treatment, whereas the static patients remained euparathyroid. The results suggest that resolution of aluminium related osteomalacia may occur with reduction in dialysis fluid aluminium, and that parathyroid hormone plays a role in the healing of aluminium related osteomalacia. The therapeutic implications are twofold: attempts to remove all traces of hyperparathyroidism may be detrimental to the bone mineralization status; and stimulation of the parathyroid glands by means of a mild reduction in dialysis fluid calcium may be of value in the management of those cases with persistent osteomalacia and low bone turnover.