Daily rhythm of creatinine in dog: clinical and diagnostic significance.

The goal of the present study was to investigate the influence of feeding and fasting on daily rhythm of serum creatinine in dogs. Blood samples from 10 purebred Beagle dogs were collected at 4-h intervals for 48 h (starting at 07:00 on day 1 and finishing at 03:00 on day 2). Statistical analysis of the data was performed by one-way repeated-measures analysis of variance (ANOVA) and by single cosinor method. Cosinor analysis identified the periodic parameters and their acrophases during the two days of monitoring. On each day, there was a highly significant effect of time in all dogs, with P values <0.05. Our results indicate the existence of a temporal relationship between serum creatinine concentration and feeding-asting cycles and suggest that food intake is a physiological trigger for the synthesis and secretion of creatinine. [ABSTRACT FROM AUTHOR]