Renal osteodystrophy in asymptomatic hemodialysis patients: evidence of a sex-dependent distribution and predictive value of serum aluminum measurements

Aluminum levels and stores in patients with total hip endoprostheses from TiAIV or TiAINb alloys

Aluminum ranks as a potentially hazardous agent. Pathologic findings in different organs show that it can accumulate in brain, muscle, liver and bone. Therefore, we investigated whether patients with cementless total hip endoprostheses made out of titanium alloys containing aluminum are at risk. In order to determine the complete aluminum body loading in patients who have had their hip replacement for a long period of time (mean 58 months), we mobilized possible stores of aluminum with desferoxamine (DFO). Electrothermal atomic absorption spectroscopy was used to quantify the level of aluminum in serum and urine before and after DFO treatment. A serum aluminum value of 10 micrograms/l or less is internationally accepted as safe. The average serum aluminum level in this study was 14.2 micrograms/l, which is slightly above the limit, but clearly below those levels which can lead to disease (> 50 micrograms/l). No relevant storage of aluminum was found. This latter finding is more important since chronically elevated aluminum levels lead to cellular deposits, which affect the cellular biochemistry. The values before and after DFO mobilization did not differ substantially, indicating that aluminum in alloys for biomaterials can be regarded as safe as far as the risk of aluminum release in vivo is concerned. Histologic studies of bone from the bone-metal interface also showed no deposits of local aluminum release.

Bone aluminum accumulation in hemodialysis patients: a longitudinal perspective

Serial bone biopsies obtained from 19 chronic hemodialysis patients asymptomatic for bone disease were examined retrospectively. We found only modest amounts of stainable bone aluminum after the first few years of hemodialysis therapy. Over the ensuing 5 to 15 years, there was a progressive increase in stainable bone aluminum (% of total bone surface): 0 to 4.9 years, 19.9 +/- 3.8% (mean +/- SEM); 5.0 to 9.9 years, 28.4 +/- 5.3%; and greater than or equal to 10.0 years, 58.0 +/- 7.7%. At final biopsy, the extent of bone surface aluminum was significantly correlated with duration of hemodialysis therapy (r = 0.54) and with bone formation rate (BFR) (r = -0.54). Patients who developed aluminum-associated bone disease did not differ from other patients in duration of hemodialysis, intake of 1-hydroxylated vitamin D3 compounds, or the findings on early bone biopsy. High-turnover renal osteodystrophy remains the dominant bone lesion throughout the course of hemodialysis in patients with intact parathyroid glands. In individual patients, bone histology frequently changes over time and in some patients, aluminum-associated bone disease may improve spontaneously. Bone biopsy in an asymptomatic patient who has received hemodialysis therapy for less than 5 years does not appear to be useful in predicting the subsequent appearance of aluminum-associated bone disease.