Renal contrast agent precautions, often including the following aspects: First, whether to stop using metformin drugs within 48 hours, because metformin drugs will affect the metabolism of the kidneys, and the contrast agent will damage the kidneys, so it will affect the renal function for a long time. Second, whether allergic to contrast medium, generally for allergic patients are not recommended to apply, preoperative contrast medium skin test can be carried out. Third, it is recommended to drink more water, especially on the day of contrast examination, to ensure that the urine volume is more than 2000ml. Fourth, because the contrast agent will damage renal function, there can be a transient renal function impairment, so it is recommended to review the renal function 2 days after the contrast agent examination, and if there is any abnormal renal function, actively apply the renal drugs and other symptomatic treatment, to prevent the disease from progressing and causing irreversible consequences.