Establishment of a time-resolved immunoassay for acute kidney injury based on the detection of Kim-1

Aim To establish a highly sensitive time-resolved fluorescence immunoassay (TRFIA) of kidney injury molecule-1 (Kim-1) and evaluate its clinical value in acute kidney injury (AKI). Methods The Kim-1-TRFIA was established by the double-antibody sandwich method, and the method was evaluated. The established Kim-1-TRFIA was used to detect the concentration of Kim-1 in the serum of healthy controls and patients with AKI. Results The optimal coating antibody concentration and optimal Eu3+-labeled antibody dilution ratio for Kim-1-TRFIA are 1 mu g/ml and 1:140, respectively. The linear range is 42.71-4666.69 pg/ml. The intra- and inter-assay coefficients of variation are <10%. The specificity of our Kim-1-TRFIA is acceptable. The recovery is between 95.14% and 102.84%. The concentration of Kim-1 in the serum of patients with AKI is 126.50 +/- 67.99 pg/ml, which is significantly higher than that in the serum of healthy controls (49.72 +/- 16.40 pg/ml, p < 0.001). Staging patients with AKI by glomerular filtration rate shows that the serum concentration of Kim-1 increases significantly with increasing disease severity (p < 0.05). Conclusion A highly sensitive Kim-1-TRFIA was established. With this immunoassay, a good differential diagnosis can be made, and healthy people and AKI patients can be differentiated by detecting the concentration of Kim-1 in the serum. Moreover, the severity of AKI patients can be determined.