The main harmful effect of urinary stones is to cause fluid accumulation in the renal pelvis and ureter and to impair kidney function, usually in a long-term chronic damage process. Sometimes unilateral renal function has been severely damaged, but the patient has no obvious signs of discomfort. Therefore, it is very important to evaluate the total and fractional kidney function in patients with urolithiasis. The main purpose of the nephrogram is to help the physician correctly evaluate the total and fractional kidney function of the patient. No special preparation is required before the test, and the test requires an intravenous injection of tracer.