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Abstract: FR-PO508

Comparison of Four Commercially Available ELISA Kits for Serum and Urinary Klotho in Mice

Session Information

Category: Bone and Mineral Metabolism

  • 401 Bone and Mineral Metabolism: Basic


  • Hamano, Naoto, Tokai University School of Medicine, Isehara, Japan
  • Komaba, Hirotaka, Tokai University School of Medicine, Isehara, Japan
  • Wada, Takehiko, Tokai University School of Medicine, Isehara, Japan
  • Fukagawa, Masafumi, Tokai University School of Medicine, Isehara, Japan

Klotho is a transmembrane protein that serves as a co-receptor for fibroblast growth factor 23 (FGF23). Klotho is cleaved and released into body fluids, including serum, urine, and cerebrospinal fluid. Soluble Klotho has been implicated in diverse of biological activities and an increasing number of studies measured serum or urinary soluble Klotho levels using commercially available ELISA kits. However, the sensitivity and specificity of these kits have been poorly studied.


We assessed the diagnostic accuracy of 4 commercially available ELISA kits for soluble Klotho using serum and urine from 3-week-old Klotho homozygous knockout (Klotho-/-), heterozygous knockout (Klotho-/+), and wild type littermate mice. We measured serum soluble Klotho with 4 kits and urinary soluble Klotho with 2 kits following the instructions of manufacturers.


Klotho-/- mice showed hyperphosphatemia, high 1,25-dihydroxyvitamin D, low PTH, increased fractional excretion of phosphate, and markedly elevated FGF23, as described previously. All 4 kits for serum soluble Klotho measurements appeared to be inaccurate, with false positive results with sera from Klotho-/- mice. As for urinary soluble Klotho measurements, we found that only a kit from Immuno-Biological Laboratories Co., Ltd. provided reasonable results. With this assay, mean±SD creatinine-adjusted urinary soluble Klotho levels in Klotho-/- mice, Klotho-/+ mice, and wild type mice were 5±2, 218±38, and 290±149 pg/g creatinine, respectively (P <0.001).


These results indicate that appropriate choice of the assay is important for accurately measuring soluble Klotho levels. For validating the function of ELISA kits, measurement of target elements with specimens of knockout animals would provide valuable information.