Alimentary pentosuria

In pentosuria L-xylulose is excreted in urine, the daily amounts varying from 1 to 4 g (H8). The urinary excretion has to be distinguished from alimentary pentosuria in which other pentoses such as arabinose, xylose, or—to a lesser extent—D-ribose are found in the urine. However, traces of L-xylulose have been found in the urine of healthy individuals (cf. Section 5.4). 

Alimentary pentosuria may follow ingestion of large quantities of fruit, with L-arabinose and L-xylose occurring in high concentrations in urine. Ribosuria may occur in some muscular dystrophy patients. In both conditions, urine is positive for reducing substances. 

Pentose metabolism is obscure. The organism has a low tolerance for these sugars, and they readily appear in the urine after ingestion of fruits and vegetable gums (alimentary pentosuria). At the same time they may be synthesised to meet the demands of the growing tissues for nucleoproteins and in the condition of congenital pentosuria they are excreted continuously, irrespective of the pentoses derived from the diet. 

Galactosuria and pentosuria, if not of alimentary origin, are caused by hereditary... 

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