Xanthinuria

Xanthinuria is a rare genetic disorder characterized by elevated levels of xanthine and hypoxanthine in the urine, leading to the formation of xanthine stones in the urinary tract. It is caused by a deficiency or absence of the enzyme xanthine oxidase (XO) or its precursor enzyme, xanthine dehydrogenase (XDH). These enzymes are responsible for converting xanthine to uric acid, which is then excreted from the body.

Symptoms:

• Renal Colic: Severe pain in the back or side due to the presence of xanthine stones in the urinary tract.
• Hematuria: Blood in the urine.
• Frequent Urination: Increased urge to urinate.
• Nausea and Vomiting: Often associated with the intense pain.

Causes:

• Xanthinuria is typically an inherited condition, passed down in an autosomal recessive pattern, meaning that both parents must carry a mutated gene for a child to inherit the disorder.
• Mutations in the genes encoding xanthine oxidase or xanthine dehydrogenase enzymes result in reduced or absent enzyme activity, leading to impaired metabolism of xanthine and hypoxanthine.

Diagnosis:

• Urinalysis: Measurement of xanthine and hypoxanthine levels in the urine, which are elevated in individuals with xanthinuria.
• Imaging Studies: Imaging techniques such as ultrasound or CT scans may be used to detect the presence of xanthine stones in the urinary tract.
• Genetic Testing: Molecular genetic testing can identify mutations in the genes associated with xanthinuria.

Treatment:

1. Fluid Intake: Increasing fluid intake to help flush out xanthine and prevent stone formation.
2. Allopurinol Therapy: Allopurinol, a xanthine oxidase inhibitor, may be prescribed to reduce the production of xanthine and prevent the formation of xanthine stones.
3. Dietary Modifications: Avoiding foods high in purines, such as organ meats, certain types of fish, and beer, can help reduce the production of xanthine.
4. Surgical Intervention: In cases where xanthine stones cause obstruction or other complications, surgical removal of the stones may be necessary.

Prognosis:

• With appropriate management, individuals with xanthinuria can lead relatively normal lives.
• Regular monitoring by healthcare providers is important to prevent complications such as kidney stones and renal impairment.

Xanthinuria requires a multidisciplinary approach to management, involving urologists, nephrologists, and geneticists, to provide comprehensive care and support to affected individuals.