Question: if a person has 4 kidneys does that mean they will excreate more Urine?

Keith Siew answered on 19 Jun 2013:

No I don’t think they would produce more urine… I think they’d produce the exact same amount as someone with two kidneys…

The body knows how much to produce to keep in balance… so it would tell each of the four kidneys to produce less… so that the sum of the four would still be equal to the sum of the two