Home ยป Creatinine the waste product closely regulated by the brain and kidneys is the end product of the metabolism of Excretory System MCQs Creatinine the waste product closely regulated by the brain and kidneys is the end product of the metabolism of January 24, 2022 88 Views Q. Creatinine the waste product closely regulated by the brain and kidneys is the end product of the metabolism of A. Ammonia B. Muscle C. Nucleotide D. Anaerobic Answer: Muscle