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Disorder of carbohydrate metabolism. Benign anomaly of the metabolism of glucuronic acid.

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Essential Pentosuria; l-Xylulosuria; Xylitol Dehydrogenase Deficiency; l-Xylulose Reductase Deficiency.

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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 extraction.

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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 Europe.

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Autosomal recessive.

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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.

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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 and minor).

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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 test papers.

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There are no considerations for this pathology, only those associated with the surgical procedure involved.

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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.

Khachadurian AK: Essential pentosuria. Am J Hum Genet 14:249, 1962.  [PubMed: 14455483]
Lane AB, Jenkins T: Human l-xylulose reductase variation: Family and population studies. Ann Hum Genet 49:227, 1985.  [PubMed: 4073836]

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