Tumor-induced osteomalacia: clinical and basic studies.

摘要: A patient with classic clinical and biochemical features of tumor-induced osteomalacia (hypophosphatemia, phosphaturia, undetectable serum concentrations 1,25-dihydroxyvitamin D [1,25(OH) 2 D]) was studied before after resection a benign extraskeletal chondroma from the plantar surface foot. Presurgical laboratory evaluation notable for normal calcium, intact parathyroid hormone (PTH), hormone-related protein (PTHrP), osteocalcin, increased alkaline phosphatase activity, frankly elevated urinary cyclic adenosine monophosphate (cAMP) pyridinium cross-link excretion. Quantitative histomorphometry showed severe deep erosions cancellous by active osteoclasts. After resection, 1,25(OH) normalized within 24 h, while renal tubular phosphorus reabsorption did not normalize until days 3, respectively; Ca declined slightly, PTH, excretion dramatically. Urinary cAMP immediately then began to increase concomitant in PTH. second bone biopsy taken 3 months demonstrated complete resolution osteomalacia, mineral apposition rate (1.09 μ/day), resorption (9.2%), mineralizing (71%), formation (0.83 mm /mm /day), marked decreases volume (13.1%) trabecular connectivity compared first biopsy. Tumor extracts affect phosphate transport epithelial cell lines or 1α-hydroxylase activity myelomonocytic line. The patient's course suggests that abnormal metabolism is due tumor product may be acting via stimulation adenylate cyclase activity. Increased prior surgical also produce an osteoclast activator. rise excretion, osteocalcin mineralization, normalization osteoid width, fall are consistent healing rapid remodeling.