Kidney Week

Abstract: FR-PO508

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

Session Information

• Bone and Mineral Metabolism: Basic
  October 26, 2018 | Location: Exhibit Hall, San Diego Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Bone and Mineral Metabolism

• 401 Bone and Mineral Metabolism: Basic

Authors

• Hamano, Naoto, Tokai University School of Medicine, Isehara, Japan

Naoto Hamano,

• Komaba, Hirotaka, Tokai University School of Medicine, Isehara, Japan

Hirotaka Komaba,

• Wada, Takehiko, Tokai University School of Medicine, Isehara, Japan

Takehiko Wada,

• Fukagawa, Masafumi, Tokai University School of Medicine, Isehara, Japan

Masafumi Fukagawa,

Background

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.

Methods

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.

Results

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).

Conclusion

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.