Osteoclast dysfunction in the osteosclerotic variant of renal osteodystrophy.

Six iliac crest bone biopsies were obtained from five patients with renal osteodystrophy and osteosclerotic lesions to investigate the mechanism of osteosclerosis in renal osteodystrophy. Each specimen was prepared in an undecalcified fashion and measured under light microscopy for routine analysis and histomorphometry. Osteoclast resorptive lacunae were estimated by measuring the lacunar length and depth. Histomorphometric studies revealed an increase in all parameters with a mean trabecular bone volume of 66% (normal: 19%-26%), mean trabecular osteoid surface of 71% (normal: 16%-22%), and a mean trabecular osteoid volume of 15% (normal: 1%-2%). In one patient, there was a ten-fold increase over the norm of osteoclasts/mm2 (0.3; normal: 0.02-0.04), whereas the mean width of trabecular bone was twice the norm. In all biopsies, the calculated lacunar area was markedly diminished compared to published controls. These results support the hypothesis that osteoclast function is impaired in patients with renal osteodystrophy.