Interpretation of serum aluminum values in dialysis patients

To determine the significance of serum aluminum levels in dialysis patients, the authors retrospectively analyzed a series of patients on maintenance hemodialysis (HD) and continuous ambulatory peritoneal dialysis (CAPD). All patients had always been treated with a dialysate containing negligible amounts of aluminum. The serum aluminum levels of hemodialysis and CAPD patients were not significantly different, not related to age or sex, and not affected by the presence of diabetes or vitamin D intake. The most important determinant of serum aluminum level in the hemodialysis patients was the current dose of aluminum-containing phosphate-binding medication. This relationship was most striking in the compliant patients. In hemodialysis patients, after an increase during the first one to two years, the aluminum levels plateaued. Aluminum levels remained stable more than five years in CAPD patients. Red blood cell mean corpuscular volume was negatively correlated with serum aluminum level. In 28 dialysis patients who had bone biopsy, aluminum levels were positively correlated to histochemical aluminum staining and bone aluminum content. A level greater than 100 ng/L was a reliable indicator of aluminum-associated osteomalacia, although a lower level did not exclude the presence of low turnover bone disease or mixed uremic osteodystrophy - two disorders possibly related to aluminum. In the presence of a high serum aluminum, elevated levels of immunoreactive parathyroid hormone (iPTH) were useful in detecting the presence of hyperparathyroidism; low levels of iPTH did not allow the authors to distinguish between other subtypes of uremic osteodystrophy.