[Renal staghorn calculi in small children - presentation of two cases].

Urolithiasis in children occurs with the incidence of 0.1-5%. Risk factors such as metabolic disorders, recurrent urinary tract infections and/or congenital abnormalities of urinary tract are detected in 75-85% of children with urolithiasis. Staghorn calculi is associated with delayed diagnosis and treatment of urinary tract infection caused by specific organisms, which produce the enzyme urease, promoting generation of ammonia and hydroxide from urea. We present two boys with staghorn calculi recognized in 8th and 31st month of age. The reason for performing ultrasonography was urinary tract infection in both boys. The younger child was previously healthy, with no symptoms of urolithiasis, the older one had recurrent urinary tract infections caused by Proteus mirabilis, episodes of anxiety and abdominal pain. Laboratory test and imaging studies excluded congenital abnormalities in the urinary tract and typical metabolic causes of urolithiasis in both boys. Treatment of infection-related stones in the younger child included two extracorporeal shock-wave lithotripsy (ESWL). In the older child, both ESWL and operation were performed. Staghorn calculi were composed of mixtures of magnesium ammonium phosphate (struvite) and calcium carbonate (apatite) and confirmed to be identified as infection-related stones. During follow-up in a nephrology outpatient clinic, values of blood pressure, renal ultrasonography, kidney function test were normal and no symptoms of urinary tract infections were clinically present. In patients with recurrent urinary tract infections, urolithiasis should be taken into consideration. The majority of staghorn calculi is often asymptomatic and can be diagnosed with an ultrasonography study performed routine or during urinary tract infection.