If a patient has hematuria, but very little urine, he most likely has acute nephritis complicated by acute renal failure, but rhabdomyolysis should be ruled out. The more common symptoms of acute nephritis are hematuria, proteinuria, edema, and hypertension. Hematuria is also clinically common, manifesting as carnal hematuria, and although this disease is relatively rare in complicating acute renal failure, it does occur. If acute nephritis is complicated by acute renal failure, the patient will have the symptoms mentioned above, appearing as hematuria of the naked eye, and the volume of urine is also relatively small. In this case, routine urine and kidney function tests should be performed to observe whether there are a large number of red blood cells in the urine, and also to observe whether creatinine and urea are significantly elevated. If the urine volume decreases further, hemodialysis treatment is needed, along with anti-infection, blood pressure control and adequate nutritional support. Although the patient’s urine is red, it is not strictly hematuria, but a kind of myoglobinuria, accompanied by a decrease in urine volume, which is caused by acute renal failure due to blockage of renal tubules by myoglobin.