Influence of coffee on the excretion of noradrenaline and adrenaline in urine. A pilot study for the comparison of two methodical models.

In field studies, the excretion rate of urinary catecholamines is very often used as an indicator of strain. Interfering effects which are due to caffeine, for example, can only be quantified if the influence of coffee consumption on the excretion of catecholamines is known quantitatively. This was the aim of our study with five subjects, on five consecutive working days, and with a strict standardization of nutrition. The urine samples were specified with respect to the following parameters: sampling period, volume, urine status, density, creatinine, noradrenaline, and adrenaline. Adrenaline showed a significant correlation with coffee consumption, whereas noradrenaline did not. Moreover, it could be demonstrated that relating the concentration of catecholamines to the creatinine excretion is insufficient for work physiology studies, especially if the urine sampling periods are as short as 2h.