Evolution of bone and plasma concentration of lanthanum in dialysis patients before, during 1 year of treatment with lanthanum carbonate and after 2 years of follow-up

Background. Lanthanum carbonate (LC) has been proposed as a new phosphate binder. Presented here are the results from one centre that participated in a multicentre trial to assess the effect of treatment with LC and calcium carbonate (CC) on the evolution of renal osteodystrophy in dialysis patients. Bone biopsies were performed at baseline, after 1 year of treatment and after a further 2-year follow-up period to assess the lanthanum concentration in bone and plasma. Methods. Twenty new dialysis patients were randomized to receive LC (median dose 1250 mg) for 1 year (n ¼ 10), followed by 2 years of CC treatment or CC (n ¼ 10) during the whole study period (3 years). Results. After 36 weeks of treatment, steady state was reached with plasma lanthanum levels varying around 0.6 ng/ml. Six weeks after cessation of 1 year of treatment, the plasma lanthanum levels declined to a value of 0.17 � 0.12 ng/ml (P < 0.05) and after 2 years to 0.09 � 0.03 ng/ml. Plasma and bone lanthanum levels did not correlate with the average lanthanum dose at any time point. The mean bone concentration in patients receiving LC increased from 0.05 � 0.03 to 2.3 � 1.6mg/g (P < 0.05) after 1 year and slightly decreased at the end of the study to 1.9 � 1.6mg/g (P < 0.05). Conclusions. Bone deposition after 1 year of treatment with LC is low (highest concentration: 5.5mg/g). There is a slow release of lanthanum from its bone deposits 2 years after the discontinuation of the treatment and no association with aluminium-like bone toxicity.