Allantoin excretion in the rat

Abstract

When nucleic acids are catabolized by the rat, most of the purine moiety is excreted in the urine as allantoin. The amount excreted has been found to be higher under physiological conditions associated with increased protein synthesis such as pregnancy and lactation (Morgan & Hanson, 1964). Other investigators (Kiriyama & Ashida, 1964) suggested that allantoin excretion is a complex function of body size and rate of growth and that it is also affected by the age of the animal and the quality of the dietary protein. However, no attempt has been made to determine quantitatively the excretion of allantoin as a function of these variables. We have examined allantoin excretion in very young and in adult rats fed on different diets and obtained two equations that can predict the allantoin excretion from the metabolic body–weight and the gain in body–weight, and from the body nitrogen content and the gain in body N.