Zimering Mark B, Caldarella Felice A, White Kenneth E, Econs Michael J
Medical Service, Veterans Affairs New Jersey Health Care System, Lyons, New Jersey 07939, USA.
Endocr Pract. 2005 Mar-Apr;11(2):108-14. doi: 10.4158/EP.11.2.108.
To describe a case of persistent tumor-induced osteomalacia, determine whether serum fibroblast growth factor-23 (FGF-23) levels postoperatively indicate incomplete tumor resection, and report lumbar spine and forearm bone mineral density (BMD) changes during 5 years of follow-up.
We present clinical, radiologic, histologic, and bone densitometry data as well as serum FGF-23 levels (determined with use of a novel C-terminal enzyme-linked immunosorbent assay) from the study patient and discuss these findings in the context of previous literature.
A 52-year-old man, who presented with muscle weakness and multiple fractures, was found to have low values for serum phosphorus, serum 1,25-dihydroxyvitamin D, and maximal tubular reabsorption of phosphate per glomerular filtration rate, a high level of serum alkaline phosphatase, and a normal serum concentration of parathyroid hormone, characteristic of tumor-induced osteomalacia. Magnetic resonance imaging to evaluate an abnormality of the left foot revealed a soft tissue mass, biopsy of which confirmed the presence of a benign, phosphaturic, mesenchymal tumor. The baseline serum FGF-23 level (2,050 RU/mL) was more than 17 times the upper limit of normal for adults (23 to 118 RU/mL) and decreased substantially within 1 day after partial resection of the tumor but remained above normal postoperatively. BMD changes indicated rapid substantial recovery of vertebral BMD but ongoing loss of forearm bone density.
The serum FGF-23 level is high in a substantial proportion of patients with tumor-induced osteomalacia. The postoperative above normal levels of serum FGF-23 correlated with known persistence of tumor in our study patient. In a patient with normal renal function, such as our study patient, levels of serum FGF-23 studied with use of the C-terminal enzyme-linked immunosorbent assay reached their nadir within 24 hours postoperatively. This result suggests that this assay can provide clinicians with rapid prognostic information in patients with known or suspected residual tumor. BMD should be assessed at both appendicular and axial sites in patients with persistent tumor-induced osteomalacia.
描述一例持续性肿瘤诱导性骨软化症病例，确定术后血清成纤维细胞生长因子23（FGF - 23）水平是否表明肿瘤切除不完全，并报告5年随访期间腰椎和前臂骨密度（BMD）的变化。
我们展示了研究患者的临床、放射学、组织学和骨密度测量数据以及血清FGF - 23水平（使用新型C端酶联免疫吸附测定法测定），并结合先前的文献讨论这些发现。
一名52岁男性，出现肌肉无力和多处骨折，血清磷、血清1,25 - 二羟维生素D以及每肾小球滤过率的最大肾小管磷重吸收率值较低，血清碱性磷酸酶水平较高，甲状旁腺激素血清浓度正常，具有肿瘤诱导性骨软化症的特征。用于评估左脚异常的磁共振成像显示一个软组织肿块，对其进行活检证实存在良性、导致磷尿的间充质肿瘤。基线血清FGF - 23水平（2050 RU/mL）超过成人正常上限（23至118 RU/mL）的17倍以上，在肿瘤部分切除后1天内大幅下降，但术后仍高于正常水平。骨密度变化表明椎体骨密度迅速大幅恢复，但前臂骨密度持续丢失。
相当一部分肿瘤诱导性骨软化症患者的血清FGF - 23水平较高。在我们的研究患者中，术后血清FGF - 23高于正常水平与已知的肿瘤持续存在相关。在肾功能正常的患者（如我们的研究患者）中，使用C端酶联免疫吸附测定法研究的血清FGF - 23水平在术后24小时内降至最低点。这一结果表明，该检测可为已知或疑似残留肿瘤的患者提供临床医生快速的预后信息。对于持续性肿瘤诱导性骨软化症患者，应在四肢和轴向部位评估骨密度。
