Bone cell biology and pediatric renal osteodystrophy

Patients with chronic kidney disease (CKD) show a broad spectrum of clinical symptoms intimately related to the disturbed mineral and bone metabolism and summarized as CKD-mineral-bone disorder (CKD-MBD). Whereas in adults an impaired bone metabolism translates mainly into an increased risk of fractures, in pediatric CKD patients rickets, skeletal deformations, and severe growth failure are additional and severe clinical findings. Further-more, an elevated Ca x P ion product, secondary hyperparathyroidism (sHPT) as well as concomitant calcitriol medication have been linked to ectopic (vascular) calcification, in which is strongly associated with the dramatically high cardiovascular morbidity and mortality even in pediatric CKD patients. Thus, in these patients the impaired mineral metabolism is the link between skeletal and cardiovascular disease. In other words, the complex interplay between kidney, skeleton, parathyroid gland, the intestine and the cardiovasculature is severely disturbed in CKD. This review summarizes the recent findings in our understanding of bone cell biology and alterations of mineral metabolism in children with CKD.