Department of Biology, Waseda University, Shinjuku, Tokyo, Japan.
R&D Headquarters, TAUNS Laboratories, Izunokuni, Shizuoka, Japan.
BMJ Open Diabetes Res Care. 2019 May 30;7(1):e000661. doi: 10.1136/bmjdrc-2019-000661. eCollection 2019.
The chronic kidney disease (CKD) is widely diagnosed on the basis of albuminuria and the glomerular filtration rate. A more precise diagnosis of CKD, however, requires the assessment of other factors. Urinary adiponectin recently attracted attention for CKD assessment, but evaluation is difficult due to the very low concentration of urinary adiponectin in normal subjects.
We developed an ultrasensitive ELISA coupled with thionicotinamide-adenine dinucleotide cycling to detect trace amounts of proteins, which allows us to measure urinary adiponectin at the subattomole level. We measured urinary adiponectin levels in 59 patients with diabetes mellitus (DM) and 24 subjects without DM (normal) to test our hypothesis that urinary adiponectin levels increase with progression of CKD due to DM.
The urinary adiponectin levels were 14.88±3.16 (ng/mg creatinine, mean±SEM) for patients with DM, and 3.06±0.33 (ng/mg creatinine) for normal subjects. The threshold between them was 4.0 ng/mg creatinine. The urinary adiponectin levels increased with an increase in the CKD risk. Furthermore, urinary adiponectin mainly formed a medium-molecular weight multimer (a hexamer) in patients with DM, whereas it formed only a low-molecular weight multimer (a trimer) in normal subjects. That is, the increase in urinary adiponectin in patients with DM led to the emergence of a medium-molecular weight form in urine.
Our new assay showed that urinary adiponectin could be a new diagnostic index for CKD. This assay is a non-invasive test using only urine, thus reducing the patient burden.
慢性肾脏病（CKD）主要基于蛋白尿和肾小球滤过率进行诊断。然而，更精确的 CKD 诊断需要评估其他因素。最近，尿脂联素在 CKD 评估中受到关注，但由于正常个体中尿脂联素浓度非常低，因此评估较为困难。
我们开发了一种超灵敏 ELISA 结合硫代烟酰胺腺嘌呤二核苷酸循环，用于检测痕量蛋白质，可在亚皮摩尔水平检测尿脂联素。我们测量了 59 例糖尿病（DM）患者和 24 例非 DM 患者（正常）的尿脂联素水平，以验证我们的假设，即由于 DM，尿脂联素水平随着 CKD 的进展而增加。
DM 患者的尿脂联素水平为 14.88±3.16（ng/mg 肌酐，平均值±SEM），正常患者为 3.06±0.33（ng/mg 肌酐）。两者之间的阈值为 4.0 ng/mg 肌酐。尿脂联素水平随 CKD 风险的增加而增加。此外，尿脂联素在 DM 患者中主要形成中等分子量的多聚体（六聚体），而在正常患者中仅形成低分子量的多聚体（三聚体）。也就是说，DM 患者尿脂联素的增加导致中等分子量形式在尿液中出现。
我们的新检测方法表明，尿脂联素可能是 CKD 的新诊断指标。该检测方法是非侵入性的，仅使用尿液，因此减轻了患者的负担。
