QPRT and acute kidney injury: Further, additional studies examining the relationship between perioperative urinary quinolinate concentration and quinolinate to tryptophan ratios and the risk of AKI, with a focus on specific vascular surgery patient populations, such as patients undergoing endovascular aortic repair and patients undergoing open vascular repair, need to be performed to determine if specific risk factors for AKI, such as exposure to high doses of iodinated contrast or aortic clamp time (ischemic time), are associated with QPRT activity and impaired NAD+ synthesis from tryptophan.