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Essential pentosuria
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Condition

Essential pentosuria

Essential pentosuria is a benign genetic condition characterized by high levels of L-xylulose sugar in the urine, occurring almost exclusively in individuals of Ashkenazi Jewish ancestry without causing any associated health problems.

Overview

Essential pentosuria is a condition characterized by high levels of a sugar called L-xylulose in the urine. The condition is so named because L-xylulose is a type of sugar called a pentose. Despite the excess sugar, affected individuals have no associated health problems.

Frequency

Essential pentosuria occurs almost exclusively in individuals with Ashkenazi Jewish ancestry. Approximately 1 in 3,300 people in this population are affected.

Causes

Essential pentosuria is caused by mutations in the DCXR gene. This gene provides instructions for making a protein called dicarbonyl and L-xylulose reductase (DCXR), which plays multiple roles in the body. One of its functions is to perform a chemical reaction that converts a sugar called L-xylulose to a molecule called xylitol. This reaction is one step in a process by which the body can use sugars for energy.

DCXR gene mutations lead to the production of altered DCXR proteins that are quickly broken down. Without this protein, L-xylulose is not converted to xylitol, and the excess sugar is released in the urine.

While essential pentosuria is caused by genetic mutations, some people develop a non-inherited form of pentosuria if they eat excessive amounts of fruits high in L-xylulose or another pentose called L-arabinose. This form of the condition, which disappears if the diet is changed, is referred to as alimentary pentosuria. Studies show that some drugs can also cause a form of temporary pentosuria called drug-induced pentosuria. These non-inherited forms of the condition also do not cause any health problems.

Associated Genes

  • DCXR

Inheritance

This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.

Other Names for This Condition

  • Essential benign pentosuria
  • L-xylulose reductase deficiency
  • L-xylulosuria
  • Pentosuria
  • Xylitol dehydrogenase deficiency

Frequently Asked Questions

Yes, certain dietary and pharmacological factors can cause temporary, non-genetic pentosuria that mimics the genetic condition. Consuming large amounts of fruits high in L-xylulose or L-arabinose, such as cranberries, can lead to alimentary pentosuria, which resolves when the diet is modified. Additionally, some medications, including certain antibiotics and antihistamines, can induce drug-induced pentosuria. If a patient has a known genetic diagnosis, these temporary factors are irrelevant, but for undiagnosed individuals, a history of recent dietary changes or new medications should be considered before confirming a genetic diagnosis.
No, essential pentosuria is a benign condition that does not increase the risk of kidney stones, urinary tract infections, or other metabolic complications. The excess L-xylulose in the urine is not fermented by bacteria in the urinary tract, so it does not create an environment conducive to infection. Furthermore, L-xylulose does not crystallize in the kidneys, so there is no associated risk of nephrolithiasis. Patients with this condition have a normal life expectancy and do not require dietary restrictions or monitoring for renal health.
Essential pentosuria is an autosomal recessive condition, meaning a person must inherit two mutated copies of the DCXR gene to have the condition. It is most prevalent in individuals of Ashkenazi Jewish descent, with a carrier frequency of approximately 1 in 10. Because the condition is benign and causes no health issues, routine screening of children is generally not recommended unless there is a specific clinical reason to distinguish it from diabetes. However, if a parent is a carrier, genetic counseling can provide information on the 25% risk of having an affected child, though testing is optional given the lack of clinical consequences.
Essential pentosuria is typically discovered incidentally during routine urinalysis when a test for glucose yields a positive result, but the patient's blood sugar levels are normal. Since standard urine dipsticks detect reducing sugars, they may flag L-xylulose as glucose. To confirm the diagnosis, clinicians order specific confirmatory tests such as a urine L-xylulose assay or genetic testing for mutations in the DCXR gene. This distinction is critical to rule out diabetes mellitus, which requires immediate treatment, whereas pentosuria requires no medical intervention.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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