IT APPEARS to be widely accepted that the urinary excretion of creatine is characteristic of childhood. Urinary creatine in children was first reported, in 1907, by Amberg and Morrill1 and later confirmed by Sedgwick,2 van Hoogenhuyze,3 Rose,4 Folin and Denis5 and others reporting before 1912. Because this substance so regularly appears in the urine of children, it is generally considered a normal metabolite, and such excretion is usually referred to as "physiological creatinuria."
Although there have subsequently been many scattered reports of its presence in urine from healthy children, the total number of determinations reported in the literature is not very impressive. Faulty or inadequately described methods of analysis have, in addition, added confusion as to its quantitative variation. It was thought that a knowledge of creatine excretion at various ages might provide some clue as to the mechanisms controlling its excretion. Further, it seemed
CLARK LC, THOMPSON HL, BECK EI, JACOBSON W. EXCRETION OF CREATINE AND CREATININE BY CHILDREN. AMA Am J Dis Child. 1951;81(6):774–783. doi:10.1001/archpedi.1951.02040030788004