Sudden urine absence in children requires prompt medical attention, the main reasons include urinary stones, urinary tract infection, bladder dysfunction, dehydration, nephritis, kidney disease, mainly as follows: 1, first clarify whether the urine volume is gradually reduced or suddenly no urine, if the first few urine volume is normal and no other symptoms, suddenly no urine, then first consider whether there are urinary stones, such as posterior urethral stones or ureteral stones, at this time there is generally crying, pain performance If you are unable to urinate with crying, you should consider urinary tract infections, such as cystitis and urethritis, because the child is afraid to urinate for fear of pain. It may also be due to neuromuscular damage, the bladder has urine but can not be solved, you can check the ultrasound to help diagnose; 3, lack of water caused by anuria, usually accompanied by vomiting, diarrhea, etc., urine volume gradually reduced, sometimes there is also a short period of anuria, clinical manifestations usually have dehydration; 4, nephritis, nephropathy generally gradually appear less urine, sometimes there is a sudden absence of urine, usually combined with swelling and other manifestations.