The present invention provides a method for diagnosing in a subject Acute Kidney Injury or a related or analogous disease state. The method comprises the steps of a) providing a sample taken from the subject: b) analysing the sample from the subject to determine the level of a biomarker selected from certain atomic species; and c) comparing the level of the biomarker in the sample to a reference level of the biomarker that is characteristic of a healthy subject, eg a subject having normal renal function. An elevated level of the biomarker in the sample relative to the reference level is indicative of Acute Kidney Injury or a related or analogous disease state. The invention also relates to the use of an atomic species selected from those in Table 1 as a biomarker for Acute Kidney Injury or a related or analogous disease state, and test kits comprising an analytical element sensitive to those biomarkers.