This study from a nephrology journal shows that urine creatinine levels are associated with lean body mass, degree of vigorous exercise, and meat in the diet: h

This study from a nephrology journal shows that urine creatinine levels are associated with lean body mass, degree of vigorous exercise, and meat in the diet: http://cjasn.asnjournals.org/content/3/2/348.full http://cjasn.asnjournals.org/content/3/2/348.full Did these authors control for any of these factors?