Noncollagenous proteins in normal and pathological human bone.

The concentrations of alpha 2HS-glycoprotein, albumin, and sialic acid were measured in the bone of 28 normal individuals and 6 patients with osteogenesis imperfecta, 3 patients with Paget's disease, and 4 patients with either renal osteodystrophy, osteoporosis, osteomalacia, or osteopetrosis. The concentration of alpha 2HS-glycoprotein in neonatal bone was 3 X higher than in bone from children and 7 X higher than in adult bone. The concentrations of albumin and sialic acid in neonatal bone were 1.5 X higher that in bone from children and twice the levels in adult bone. The concentrations of alpha 2HS-glycoprotein, albumin and sialic acid were above the normal mean values in the patients with osteogenesis imperfecta, and 4 patients had significantly raised levels of one or more of these proteins. The concentrations of these noncollagenous proteins were also significantly raised in Paget's disease, and the alpha 2HS-glycoprotein was significantly raised in renal osteodystrophy. The lowest level of alpha 2HS-glycoprotein was in osteopetrotic bone and the lowest levels of albumin and sialic acid were in osteoporotic bone. The results of this study suggest that the concentrations of alpha 2HS-glycoprotein, albumin, and sialic acid in bone are related to the rate of bone turnover.