What is the reason for the low urine volume of 4-month infants?

There are many reasons for the low urine volume of 4-month-old infants. If the milk powder given to the infant is too thick and the living environment is too hot, the child will sweat more, which will lead to concentrated urine and reduced urine volume; in addition, it may be caused by kidney diseases; fever, gastroenteritis, diarrhea and pneumonia will also lead to oliguria.