“…The merits of expressing the output of urinary metabolites on the basis of creatinine excretion as opposed to 24-hour collections has been debated (Vestergaard and Leverett, 1958;Cramer, Cramer, and Selander, 1967;Applegarth, Hardwick, and Ross, 1968;Gitlow et al, 1968). The convenience of the former approach cannot be denied, particularly where a complete collection of the specimen is difficult, as in young children (Gitlow et al, 1968).…”