UNASSIGNED: We present the case of a 37-year-old man with active Crohn\'s disease, presenting with difficulty walking and fractures of the vertebrae and calcaneus. He had long-standing hypophosphatemia. Nutritional causes for hypophosphatemia were considered in the first instance given the presence of chronic diarrhea and vitamin D deficiency; however, there was minimal response to appropriate supplementation with oral phosphorous and vitamin D. Iron infusion-induced hypophosphatemia was then considered, but the nadir phosphate level preceded any iron infusion. Therefore, work-up was undertaken for less common causes. He was ultimately diagnosed with tumor-induced osteomalacia, caused by excess fibroblast growth factor 23 (FGF23) secretion from a phosphaturic mesenchymal tumor about the knee. He had complete resolution of symptoms and biochemical abnormalities following successful resection of the tumor.
UNASSIGNED: This case illustrates the approach to investigation of hypophosphatemia in IBD patients. If the time course and response to phosphate supplementation are not as expected for nutritional or iron infusion-induced hypophosphatemia, less common causes should be considered.
■我们介绍了一名37岁男子患有活动性克罗恩病的病例,表现为行走困难,椎骨和跟骨骨折。他长期患有低磷酸盐血症。由于存在慢性腹泻和维生素D缺乏,首先考虑了低磷酸盐血症的营养原因;然而,对适当补充口服磷和维生素D的反应最小。然后考虑了铁输注引起的低磷酸盐血症,但是磷酸盐水平的最低点先于任何铁输注。因此,工作是针对不太常见的原因进行的。他最终被诊断出患有肿瘤诱导的骨软化症,由膝关节周围磷性间充质肿瘤分泌过多的成纤维细胞生长因子23(FGF23)引起。成功切除肿瘤后,他的症状和生化异常完全缓解。
■本案例说明了IBD患者低磷酸盐血症的研究方法。如果营养或铁输注引起的低磷酸盐血症的时程和对磷酸盐补充的反应不如预期,应该考虑不太常见的原因。