Disorder of carbohydrate metabolism. Benign anomaly of
the metabolism of glucuronic acid.
Essential Pentosuria; l-Xylulosuria; Xylitol
Dehydrogenase Deficiency; l-Xylulose Reductase Deficiency.
Inborn error of metabolism in which 1.0 to 4 g l-xylulose is excreted in the urine each day. It is a benign metabolic
disturbance, which occurs almost exclusively in Ashkenazim of Polish-Russian
1:40,000 to 1:50,000 in the U.S. population; the
frequency in Ashkenazim may be as high as 1:2500 and is 1:5000 in Israeli
Jews. In the vast majority of cases, antecedents have been traced to Eastern
Essential pentosuria is the result of a partial
deficiency of l-xylulose reductase in the glucuronic acid oxidation
pathway. The basic fault concerns nicotinamide adenine dinucleotide
phosphate (NADP)-linked xylitol dehydrogenase.
l-Xylose dehydrogenase converts l-xylose to
xylitol. Xylitol is converted to d-xylose, which becomes d-xylose-5-phosphate and enters the pentose phosphate shunt. Deficiency of
this enzyme leads to increased concentration of l-xylose in the blood
and urine. No therapy is required. Red cells from pentosuric patients
contain only the minor l-xylulose reductases isozyme (normally major
Affected individuals cannot degrade l-xylulose derived from glucuronic acid. It is a benign condition that is
of clinical significance only when confused with diabetes mellitus. Blood
sugar is normal. The pentose (urine) does not react with glucose oxidase
There are no considerations for this
pathology, only those associated with the surgical procedure involved.
Alimentary Pentosuria: Arabinose or xylose is found in the
urine of normal people following the ingestion of very large quantities of
fruits such as cherries, grapes, and fruit juices. Large quantities of d-ribose may be found in the urine of some patients with muscular
dystrophy, probably as a result of breakdown of ribose-containing
nucleotides in degenerating muscle.
Lane AB, Jenkins T: Human l
-xylulose reductase variation: Family and
population studies. Ann Hum Genet