Circadian rhythms of urinary excretions of water and electrolytes in patients receiving total parenteral nutrition (TPN).

In order to determine whether the usual feeding pattern actually modifies the circadian rhythms of urinary excretion of water and electrolytes, we compared the circadian rhythm characteristics in patients receiving total parenteral nutrition (TPN group) with those in patients on an ordinary hospital diet (control group). Statistically significant circadian rhythms were detected in all of the urinary variables investigated herein by using the population mean-cosinor method in both groups. In addition, there were no statistically significant differences of the mesor, the %-amplitude and the acrophase between the two groups. These results suggest that the usual feeding pattern is not a main determinant in forming the circadian rhythm characteristics of human urinary variables.