Bone
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Case Reports
Diagnostic utility of magnetic resonance imaging skeletal survey in a patient with oncogenic osteomalacia.
Oncogenic osteomalacia is a rare paraneoplastic syndrome characterized by hypophosphatemic osteomalacia due to renal phosphate wasting. The same biochemical features are found in patients with X-linked hypophosphatemic rickets/osteomalacia and sporadic hypophosphatemic osteomalacia with unknown etiology. Oncogenic osteomalacia is cured by resection of the responsible tumor. ⋯ Resection of the tumor resulted in normalization of serum phosphate and renal phosphate handling. Because the most frequent causes for oncogenic osteomalacia are tumors in bone or soft tissue, magnetic resonance imaging skeletal survey is a very powerful method for detecting the responsible tumor. Vigorous search for tumors with this method in patients with hypophosphatemic osteomalacia would be helpful not only for proper management of patients, but also for clarifying the identity of sporadic hypophosphatemic osteomalacia.
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Tibolone is a synthetic steroid with tissue-specific estrogenic, progestogenic, and androgenic properties. The therapeutic effects of tibolone on bone mass and strength, bone metabolic markers, and indices of histomorphometry were investigated in ovariectomized (ovx) rats on a low (0.1%)-calcium diet in comparison with 17alpha-ethynylestradiol (EE) or 1alpha-hydroxyvitamin D3 [1alpha(OH)D3]. Tibolone (0.1-3 mg/kg/day), EE (0.1 mg/kg/day), or 1alpha(OH)D3 (0.5 microg/kg/day) was administered orally once a day for 16 weeks, starting 12 weeks after ovariectomy, when the bone mineral density (BMD) of lumbar vertebrae (L4-5) and femur (global, proximal, and distal regions) had already been decreased by the combination of ovariectomy and low dietary calcium. ⋯ Tibolone or EE decreased serum levels of osteocalcin and bone alkaline phosphatase and urinary levels of deoxypyridinoline and pyridinoline compared with the ovx control group. Furthermore, tibolone or EE decreased the mineralizing surface and bone formation rate as well as the osteoclast surface and osteoclast numbers. 1Alpha(OH)D3, however, did not affect these serum and urinary parameters. These data suggest that tibolone suppresses the accelerated bone turnover induced by a combination of ovariectomy and low dietary calcium, and indicate that tibolone may be a potentially useful drug for the treatment of postmenopausal osteoporosis.