Allantoin urinary excretion

Purines are metabolized in a series of reactions involving hypoxanthine, xanthine, uric acid, and allantoin as end products that are subsequently excreted in urine. Fig. 3 shows the metabolic pathways for xanthine. Measurement of urinary excretion of purine metabolites, primarily allantoin or, additionally, uric acid, xanthine, and hypoxanthine, has been proposed as a marker for microbial... 

Creatinine and purine derivatives—allantoin, uric acid, hypoxanthine, and xanthine present in biological samples— are important analytes for diagnoses of certain types of metabolic diseases and can serve as markers for these processes. Analyses for such substances are cmcial for diagnosis and the monitoring of renal diseases, metabolic disorders, and various types of tumorigenic activity. On the contrary, these compounds are very important in the field of animal nutrition, because the measurement of their urinary excretion is being used as an internal marker for microbial protein synthesis. 

Table lO-II gives the results of one study of urinary excretion in man of allantoin and of purines other than uric acid (4 ). In addition, 1-methyl-adenine, iS -methyladenine, iVMimethylguanine, iV -methyladenosine, adenosine, and 1-methylguanosine have also been reported to be in human urine (43). The methylated purines are believed to be derived mainly from the catabolism of transfer RNA. 

In vivo xanthine oxidase inhibition results in a reduction of uric acid (and allantoin) in urine and in an increase in the urinary excretion of hypoxanthine and xanthine as described by Elion 1 for allopurinol. The dose-dependence of the excreted amounts of hypoxanthine and xanthine is a relevant consideration when using these parameters to measure the action of uricostatics in the rat. The purpose of our studies was to obtain a simple and rapid method to detect the uricostatic quality of hypouricemic compounds. 

In the pig allantoin represents the principal end product of purine metabolism case and uric acid excretion amoimts to less than 100 mg/day. On 400 mg of Thiopurinol per day (Table h) the only urinary constituent to show any effect from the therapy was the urinary uric acid level which fell by about 303. Total purine excretion was relatively unaffected and fell at the most by As in the three human studies no alteration in Xanthine... 

Oxonic acid is a uricase inhibitor (6) and has been given to rodents to produce an animal model for gout (7). When given to pigs urinary allantoin excretion decreased, as uric acid excretion increased. These findings indicate inhibition of the enzyme uricase. However, oxonic acid also produced a great increase in orotic acid and orotidine excretion. Urinary levels increased from 5 nig to 900 mg/2A hours, and this would imply a complete or... 

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