Pediatric anuria is defined as less than 30-50ml of urine per day or less than 50ml/m^2 considered as anuria. Individual differences in the volume of urine in children are relatively large. 48 hours after birth, the normal volume of urine in newborns is usually 1-3ml/kg per hour. 400-500ml per day for normal infants, 500-600ml for toddlers, 600-800ml for preschoolers, and 800-1400ml for school-age children are considered oliguria when the daily volume of urine is less than 400ml for school-age children, less than 300ml for preschoolers, and less than 200ml for infants. Less than 300ml and less than 200ml for infants and toddlers is oliguria. Common causes of oliguria and anuria can be dehydration due to diarrhea, acidosis or kidney disease such as acute renal failure.