IGFBP7 and acute kidney injury: ATI as the primary lesion of COVID-19-associated AKI is also consistent with a urinary-biomarker study demonstrating that COVID-19 patients with stage 2 and 3 AKI have elevated levels of urinary [TIMP-2] • [IGFBP7] and tubular (α-1-microglobulin) proteinuria [24,78].