title: Serum osteocalcin in the treatment of inherited rickets with 1,25-dihydroxyvitamin D3.
abstract: Osteocalcin is a vitamin K-dependent protein, synthesized in bone, which can be detected in serum. We have measured circulating osteocalcin levels in 10 patients with x-linked hypophosphatemia (XLH) and in 6 patients with autosomal recessive vitamin D dependence (ARVDD) who started 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3] therapy. Patients with XLH were studied before and after 7-12 months of therapy that included 1,25-(OH)2D3 (10-72 ng/kg x day) and oral phosphate. Serum osteocalcin rose from 28 +/- 12 to 52 +/- 12 ng/ml (mean +/- SE; P less than 0.01) in concert with improvements in biochemical status and bone mineralization. Vitamin D therapy was withdrawn for 2 weeks from patients with ARVDD. The vitamin D-deplete status was evidenced by low 1,25-(OH)2D3 levels (12 +/- 2 pg/ml; n = 6). After 1 week of therapy with 1,25-(OH)2D3, serum calcium rose from 9.03 +/- 0.21 to 9.67 +/- 0.25 mg/dl (P less than 0.002), while serum phosphorus and alkaline phosphatase remained unchanged. Serum osteocalcin rose from 35 +/- 7 to 83 +/- 32 ng/ml (P less than 0.05). At 3 weeks, serum calcium remained elevated (9.63 +/- 0.18 ng/dl) over control levels (P less than 0.01); phosphorus and alkaline phosphatase were still unchanged. Serum osteocalcin rose to 114 +/- 42 ng/ml, significantly greater than values at 1 week (P less than 0.05). Thus, serum osteocalcin increases after 1,25-(OH)2D3 therapy in both ARVDD and XLH.
mesh_terms: D000293:Adolescent; D000328:Adult; D000375:Aging; D000469:Alkaline Phosphatase / Q000097:blood; D002117:Calcitriol / Q000627:therapeutic use*; D002118:Calcium / Q000097:blood; D002135:Calcium-Binding Proteins / Q000097:blood*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D008297:Male; D015675:Osteocalcin; D010758:Phosphorus / Q000097:blood; D012279:Rickets / Q000097:blood / Q000188:drug therapy / Q000235:genetics*; D014960:X Chromosome
chemical_list: D002135:Calcium-Binding Proteins; D015675:Osteocalcin; D010758:Phosphorus; D000469:Alkaline Phosphatase; D002117:Calcitriol; D002118:Calcium