When doing enhanced CT and angiography, a necessary step is to inject contrast to make the images clearer. However, the contrast agent is toxic, so the general public should drink more water after the test, while the high-risk group should be “medically hydrated”. The “high-risk groups” mentioned here mainly refer to people over 70 years old, diabetic patients and people with abnormal kidney function. Medical rehydration” is a medical term. A few hours before doing angiography, especially interventional treatment such as stent placement, a certain amount of glucose or saline needs to be injected first, the amount is about 1000 ml, this process is called “medical rehydration This process is called “medical rehydration”, also known as “hydration”. After the imaging test, the patient needs to be fully hydrated again, with additional fluids and a small amount of diuretics in moderation. This can reduce blood viscosity, increase renal blood flow, relieve renal vasoconstriction, enhance metabolism, and promote the discharge of contrast agent to reduce the occurrence of contrast nephropathy. Many people may ask, since hydration can achieve the effect of blood thinning and promote metabolism, is it not more convenient to drink more water directly? Drinking more water will promote metabolism, but water is not recommended before the contrast examination to avoid patients’ allergic reactions, which may lead to vomiting and easily cause choking. Even after the examination, patients can drink more water to promote metabolism, but it is not advocated to drink too much, too much water will cause bloating and other uncomfortable symptoms, Director Zheng Yuehong stressed that if the kidney function is not good metabolism, drinking more water in and out is also easy to cause edema, causing water and electrolyte imbalance, in fact, is also increasing the burden on the kidneys. For patients with poor kidney function and other chronic diseases such as hypertension and diabetes, drinking water can be done as long as it is half as much as the usual normal amount of water. In addition to hydration, you can eat more liquid or light food, more grains and cereals, vegetables and fruits, and less and more meals after the imaging examination.