Division of Nephrology and Endocrinology, Department of Medicine, University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan.
J Bone Miner Metab. 2012 Mar;30(2):217-21. doi: 10.1007/s00774-011-0306-4. Epub 2011 Sep 7.
Fibroblast growth factor 23 (FGF23) is a hormone regulating phosphate and vitamin D metabolism. We have previously established a sandwich enzyme-linked immunosorbent assay (ELISA) for FGF23 and reported that FGF23 values are useful for the differential diagnosis of chronic hypophosphatemia. However, this ELISA has a rather narrow assay range of 3-800 pg/ml, and it was pointed out that the assay performance is not satisfactory when automatic washing is used. Here we evaluated a new automated chemiluminescence immunoassay for FGF23. This assay uses 10 μl sera or plasma samples and requires 20 min to obtain the first result. The assay was linear up to about 15,000 pg/ml and had a detection limit of 1 pg/ml. In addition, this assay showed coefficients of variation of less than 5% using samples with average FGF23 levels of 43.2-2,454.0 pg/ml. When FGF23 levels in 210 samples from chronic hypophosphatemic patients were evaluated by both the previous ELISA and this new assay, there was a good correlation of R (2) = 0.96. However, FGF23 levels by the new assay showed lower values, especially in samples with high FGF23 levels. Given that the lowest FGF23 level in patients with FGF23-related hypophosphatemia was 30.8 pg/ml and that the highest FGF23 levels in patients with non-FGF23-related hypophosphatemia was 20.8 pg/ml by this novel assay, the sensitivity and specificity were 100% when the cutoff was set between 20.8 and 30.8 pg/ml. From the aspect of convenience and the coefficients of variation of this assay, we propose that the cutoff be 25 pg/ml. There results indicate that this new assay is ideal for both clinical use and clinical studies, especially when measuring many samples with high FGF23 levels.
成纤维细胞生长因子 23（FGF23）是一种调节磷酸盐和维生素 D 代谢的激素。我们之前建立了一种成纤维细胞生长因子 23 的夹心酶联免疫吸附测定法（ELISA），并报道 FGF23 值可用于慢性低磷血症的鉴别诊断。然而，这种 ELISA 的测定范围相当狭窄，为 3-800pg/ml，并且当使用自动洗涤时，其测定性能并不令人满意。在此，我们评估了一种新的自动化化学发光免疫分析法用于检测 FGF23。该测定法使用 10μl 血清或血浆样本，并且需要 20 分钟才能获得第一个结果。该测定法的线性范围约为 15,000pg/ml，检测限为 1pg/ml。此外，当使用平均 FGF23 水平为 43.2-2454.0pg/ml 的样本时，该测定法的变异系数小于 5%。当用之前的 ELISA 和新的测定法评估 210 例慢性低磷血症患者的 FGF23 水平时，两者的相关性良好（R2=0.96）。然而，新测定法的 FGF23 水平显示出较低的值，特别是在 FGF23 水平较高的样本中。鉴于 FGF23 相关低磷血症患者的最低 FGF23 水平为 30.8pg/ml，而非 FGF23 相关低磷血症患者的最高 FGF23 水平为 20.8pg/ml，因此，当将截断值设置在 20.8 和 30.8pg/ml 之间时，该测定法的灵敏度和特异性均为 100%。从该测定法的便利性和变异系数方面考虑，我们建议将截断值设置为 25pg/ml。这些结果表明，该新测定法既适用于临床应用，也适用于临床研究，特别是在测量具有高 FGF23 水平的大量样本时。
