Summary about Disease
Xanthinuria type I is a rare genetic disorder in which the body lacks the enzyme xanthine dehydrogenase. This enzyme is necessary for breaking down xanthine and hypoxanthine, which are purine bases. The deficiency leads to an accumulation of these substances in the blood and urine, potentially causing various health issues.
Symptoms
Many individuals with xanthinuria type I are asymptomatic. When symptoms do occur, they can include:
Kidney stones (xanthine stones) leading to:
Flank pain
Blood in the urine (hematuria)
Urinary tract infections
Muscle problems (rare)
Arthritis (rare)
Renal failure (very rare)
Causes
Xanthinuria type I is caused by mutations in the XDH gene, which provides instructions for making the enzyme xanthine dehydrogenase. It is inherited in an autosomal recessive manner, meaning that both parents must carry a copy of the mutated gene for their child to be affected.
Medicine Used
There is no specific medication to directly replace the missing enzyme. Treatment focuses on managing symptoms and preventing complications. Allopurinol is NOT used in Type I. Treatment and management is primarily done through dietary means.
Increased fluid intake: Drinking plenty of water helps dilute xanthine and promotes its excretion in the urine, reducing the risk of stone formation.
Alkalinizing agents: Potassium citrate or sodium bicarbonate may be prescribed to raise the pH of the urine, further helping to dissolve xanthine crystals.
Is Communicable
No, xanthinuria type I is not communicable. It is a genetic disorder and cannot be spread from person to person.
Precautions
The primary precautions involve dietary modifications and lifestyle adjustments to minimize xanthine and hypoxanthine buildup.
Low-purine diet: Reduce consumption of purine-rich foods such as red meat, organ meats, seafood (especially shellfish), and certain vegetables like spinach, asparagus, and mushrooms.
Hydration: Maintain adequate fluid intake throughout the day.
Regular monitoring: Periodic kidney function tests and urine analysis are important to detect any complications early.
Avoid dehydration: Especially during exercise or in hot weather.
How long does an outbreak last?
Xanthinuria type I isn't characterized by "outbreaks." It's a chronic condition. The symptoms such as kidney stones can cause episodes of pain and discomfort which will last until the stone passes or is medically removed. The underlying condition remains lifelong.
How is it diagnosed?
Diagnosis typically involves:
Urine analysis: Detecting elevated levels of xanthine and hypoxanthine in the urine.
Blood tests: Measuring uric acid levels (which may be low or normal) and kidney function.
Kidney stone analysis: If stones are present, analyzing their composition to confirm they are xanthine stones.
Genetic testing: Confirming the diagnosis by identifying mutations in the XDH gene.
Enzyme assay: Measuring the activity of xanthine dehydrogenase in a liver biopsy (rarely performed).
Timeline of Symptoms
Symptoms can present at any age, from infancy to adulthood, or may never appear at all. Some people may have no symptoms their entire lives.
Infancy/Childhood: If symptomatic, kidney stones may appear.
Adulthood: If symptomatic, kidney stones and associated symptoms may appear.
Important Considerations
Genetic counseling: Recommended for families with a history of xanthinuria to understand the risk of inheritance.
Differential diagnosis: It's crucial to differentiate xanthinuria type I from other conditions that cause kidney stones or low uric acid levels, such as molybdenum cofactor deficiency.
Long-term management: Regular monitoring of kidney function and adherence to dietary recommendations are essential for preventing complications.
Consultation with specialists: Nephrologists, geneticists, and dietitians can provide specialized care and guidance.
Avoid certain medications: Some medications can increase xanthine levels. Discuss all medications with your healthcare provider.