History
Symptoms are nonspecific and relate to the underlying pathophysiology and secondary complications. In young children, irritability, vomiting, and failure to thrive may be the presenting symptoms. At any age, the patient may present with gross or microscopic hematuria, pyuria, renal colic, dysuria, urinary frequency, urine incontinence, polyuria, abdominal pain, or symptoms of a urinary tract infection. Joint pain and muscle cramps or muscle pain are symptoms of the arthropathy and myopathy, respectively.
Moreover, about two thirds of patients are asymptomatic and present with an incidental finding of extremely low levels of uric acid in the blood. [4] In nine cases of hereditary xanthinuria reported by Sebesta et al, all of the patients presented with profound hypouricemia and four were asymptomatic. [5]
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Renal system symptoms are not specific to xanthinuria and are typical of any cause of crystal nephropathy and stone formation.
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Gross or microscopic hematuria may occur as a result of crystalluria or nephrolithiasis.
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Renal colic is characterized by sudden onset of severe usually unilateral flank pain that may radiate toward the inguinal area.
Nausea and vomiting may accompany the episode.
In young children or infants, renal colic may present as irritability or unexplained abdominal pain.
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Urinary tract infection is a frequent complication of any foreign body in the urinary system.
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Acute renal failure may be the presenting feature of bilateral obstructing urolithiasis or crystal nephropathy.
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Passing a urinary stone may be the initial clinical manifestation.
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Myopathy usually occurs in older patients and is related to accumulation of xanthine. The symptoms may include muscle cramps, pain, or tightness in the hands, legs, or jaw. Muscle pain can follow vigorous exercise.
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Joint pain and stiffness are features of arthropathy.
Physical Examination
No specific physical examination findings lead to the diagnosis of xanthinuria. Failure to thrive, recurrent emesis, and irritability are nonspecific findings in young children with renal failure or urolithiasis.
Fever, flank pain, dysuria, urinary frequency, and urinary urgency are features of a urinary tract infection, which can accompany xanthinuria. Renal colic is a common presenting feature of urolithiasis. Hematuria is a typical feature of urolithiasis and crystalluria.
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Purine metabolic pathway.
