PURPOSE Hypophosphatemia (HP) can be observed in patients evaluated for skeletal fragility. We investigated prevalence of HP among outpatients referred for low bone density or fragility fractures, HP-associated clinical and biochemical features and outcomes of recommended diagnostic algorithm in our cohort. METHODS Chronic HP (phosphate ≤ 2.7 mg/dL over 6 months or longer) was retrospectively investigated among 2319 patients. In renal wasting-related HP, intact FGF23 was assessed; non-suppressed FGF23 prompted the performance of 68Ga-DOTATOC PET/CT in the suspicion of tumor-induced steomalacia (TIO). RESULTS Renal wasting-related HP (median 2.2, range 1.6-2.6 mg/dL) was observed in 19 patients (0.82%). FGF23 levels were suppressed in two patients diagnosed with renal tubular disease, increased in one and within normal range in most patients. X-linked hypophosphatemic rickets was diagnosed in one woman. In the remaining 16 patients, highly prevalent fragility fractures (50%) and severely reduced bone mineral density were detected, though diagnostic criteria for osteomalacia were not fulfilled. 68Ga-PET was performed in nine patients and was positive in four. While intact FGF23 levels alone failed to differentiate PET's outcomes (positive: FGF23 median 70.5 pg/mL; negative: 52 pg/mL, P = 0.462), the coexistence of multiple biochemical and radiologic alterations performed better in prediction of PET's positivity. CONCLUSION Mild, apparently unexplained HP is observed in 0.82% of patients with low bone density or fragility fractures. In asymptomatic patients with isolated mild hypophosphatemia, the probability of finding an underlying tumor disease is very low, and utility of extensive and expensive diagnostic workup should be carefully considered in this setting.

中文翻译：

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低骨矿物质密度和脆性骨折患者的FGF23相关性低磷血症：诊断和管理上的挑战。

目的在评估骨骼脆弱性的患者中可观察到低磷酸盐血症（HP）。我们对队列中低骨密度或易碎性骨折，HP相关的临床和生化特征以及推荐的诊断算法的结局推荐的门诊患者中的HP患病率进行了调查。方法回顾性研究2319例患者中的慢性HP（磷酸盐≤2.7 mg / dL，历时6个月或更长时间）。在与肾脏消瘦相关的HP中，评估了完整的FGF23。非抑制性FGF23提示68Ga-DOTATOC PET / CT在怀疑肿瘤诱发的血脂减少（TIO）方面的表现。结果在19例患者中观察到与肾脏消耗相关的HP（中位数2.2，范围1.6-2.6 mg / dL）（0.82％）。在两名诊断为肾小管疾病的患者中，FGF23水平受到抑制，在大多数患者中，FGF23的水平在正常范围内升高。一名妇女被诊断出X连锁低磷酸盐血症性ets病。在其余的16例患者中，尽管未达到骨软化症的诊断标准，但仍检出了高度普遍的脆性骨折（50％）和严重降低的骨矿物质密度。9例患者进行了68Ga-PET检查，其中4例为阳性。尽管仅完整的FGF23水平无法区分PET的预后（阳性：FGF23中位数为70.5 pg / mL；阴性：52 pg / mL，P = 0.462），但多种生化和放射学改变的共存在预测PET阳性方面表现更好。结论在0.82％的低骨密度或脆性骨折患者中观察到轻度，明显无法解释的HP。在患有轻度低磷血症的无症状患者中，发现潜在的肿瘤疾病的可能性非常低，