Changes in plasma bone GLA protein during treatment of bone disease

Abstract

Bone Gla protein (BGP) was measured in the plasma by radioimmunoassay (RIA) during treatment of 59 patients with bone diseases including Paget's disease (N = 9), primary hyperparathyroidism (N = 25), chronic renal failure (N = 20), and cancer involving bone (N = 5). Plasma BGP was increased above normal in all patients. BGP decreased in the patients with Paget's disease following the acute and chronic administration of salmon calcitonin. Plasma BGP was higher in women then in men with primary hyperparathyroidism. Following parathyroidectomy, BGP decreased in both sexes but the decrease was significant in women only. Plasma BGP was increased in patients with renal osteodystrophy and did not change after hemodialysis. In the patients with bone cancer, plasma BGP decreased during treatment of the attendant hypercalcemia with salmon calcitonin. Although plasma BGP and serum alkaline phosphatase (AP) levels were generally correlated in these studies, there were examples of dissociation between the two. The measurement of plasma BGP appears to provide a specific index of bone metabolism that may in some circumstances be more sensitive than serum alkaline phosphatase measurement. However, further studies are necessary to establish the clinical value of plasma BGP measurement by RIA in the management of patients with bone diseases.

Measurement of osteocalcin

“…3 1. [38][39][40] Osteomalacia In osteomalacia, serum osteocalcin correlates with parameters of osteoid formation and is significantly elevated. This is due to secondary hyperparathyroidism and to the defect in mineralization in osteomalacia, which prevents the incorporation of de novo osteocalcin into the bone and results in raised serum concentration.…”

“…The reason for this discrepancy is not known, but it could relate to the greater affinity of osteocalcin for the woven bone of Paget's disease. 39 58 in which 2 JIg calcitriol per day is given orally and the osteocalcin response at 7 days is used to assess osteoblast responsiveness. Glucocorticoids, on the other hand, decrease serum osteocalcin within a day of starting therapy and t~e effect is dose-dependent.59-64 Low osteocalcm.…”

Multiple immunoreactive forms of osteocalcin in uremic serum.

“…Although Gla residues cause osteocalcin to bind tightly to hydroxyapatite (5), nanomolar concentrations can be detected in serum by ra-dioimmunoassay (6). Increased osteocalcin levels are found in the circulation of patients with disorders characterized by increased bone turnover (7)(8)(9) and are normal in nonazotemic patients with nonosseous diseases (10). Osteocalcin has, therefore, become regarded as specific marker for bone formation (1 1).…”

Concentrations of Serum Markers of Type I Collagen Synthesis and Degradation and Serum Osteocalcin in Maternal and Umbilical Circulation.

“…Osteocalcin is the most abundant noncollagenous protein in bone and may represent a specific index of bone turnover [1,2]. These proteins are released into the serum at concentrations correlated with the rates of bone formation and resorption [5][6][7][8] …”