Mineral metabolism in chronic renal failure with special reference to serum concentrations of 1.25(OH)2D and 24.25(OH)2D.

This study examines the interrelationship between serum levels of substances important in mineral metabolism including the 3 vitamin D metabolites 25OHD, 24.25(OH)2D and 1.25(OH)2D and static and dynamic histomorphometric measurements of bone remodelling in iliac crest biopsies in 17 patients with chronic renal failure. No correlation was found between the serum values of any of the vitamin D metabolites and the histomorphometric values. However, significant inverse correlations were found between serum calcium and both the osteoid surface extent (P less than 0.05) and osteoid volume (P less than 0.05) in trabecular bone. Serum immunoreactive parathyroid hormone (iPTH) was positively related to trabecular osteoclastic bone resorption. The serum level of 1.25(OH)2D was inversely related to endogenous creatinine clearance (P less than 0.01). These results support the hypothesis that the serum calcium concentration is more important than the serum concentration of vitamin D metabolites for bone remodelling in chronic renal failure.