Renal calyceal microlithiasis: clinical presentation may precede sonographic evidence

Calyceal microlithiasis (CM) is characterized by the sonographic finding of hyperechogenic spots less than 3 mm in diameter in renal calyces, and it may be the first step in calculus formation. From January 1992 to January 1998, we have observed 216 children with CM. The present report deals with 34 of them in whom renal sonography was negative at first observation and the diagnosis of CM was made only on repeated sonographic examinations. The presenting symptoms were recurrent abdominal pain, dysuria, and hematuria occurring alone or in combination. Half of the patients had hypercalciuria. A history of urolithiasis in at least one first- or second-degree relative was present in 85% of patients. Renal sonography was repeated after 6-22 months (mean 11) and showed unilateral CM in 16 subjects and bilateral in 18. The finding of CM may be preceded by a period of time when symptoms and/or signs are present while microcalculi are not yet detectable. Repeated ultrasound examinations may be needed not only in patients with hypercalciuria but also in those with recurrent abdominal pain, dysuria, and/or hematuria not associated with hypercalciuria.