Concentration compared with total urinary excretion of 11,17‐DOA in cynomolgus monkey urine

Strees sensitive molecules exhibit great variation in concentration in the circulation and it may often be advantageous to quantify these in urine or feces rather than in serum or plasma. We advocate that all urine-or feces-should be collected, and that excretion of stress sensitive molecules should be expressed as amounts excreted per time unit per kg body-weight, rather than being expressed as concentrations in samples. Urine and feces excretion varies significantly within and between animals over time, which may render simple concentration measures of molecules of little biological relevance.