alpha-Klotho is unstable in human urine

作者：Adema Aaltje Y; Vervloet Marc G; Blankenstein Marinus A; Heijboer Annemieke C^*

来源：Kidney International, 2015, 88(6): 1442-1444.

DOI：10.1038/ki.2015.238

• catheter urine
• protease inhibitor
• stability
• alpha-Klotho

alpha-Klotho is an interesting new biomarker in kidney and cardiovascular disease. As alpha-Klotho is primarily expressed in renal epithelial tissue, various papers have reported a-Klotho concentrations in urine. As these studies did not address the reliability of urinary alpha-Klotho measurements and as urine is known to be a complex milieu, we investigated the stability of alpha-Klotho in both fresh catheter and fresh voided urine. a-Klotho was measured in these fresh urine samples and in the same samples under several other conditions. Storage of fresh catheter urine for 3 h at 37 degrees C, comparable to storage in the bladder, led to a 82% decrease in a-Klotho concentrations. Compared with fresh voided urine, alpha-Klotho concentrations decreased on an average of 45 and 82% after storage at - 80 degrees C and - 20 degrees C, respectively. An additional freeze-thaw cycle further decreased alpha-Klotho concentrations. The addition of a protease inhibitor or 0.1% albumin partly prevented degradation in fresh voided urine. Thus, alpha-Klotho is highly unstable in urine. Future studies showing results of urinary alpha-Klotho should mention conservation conditions and prove the reliability of the alpha-Klotho measurements.

• 出版日期2015-12