Evaluation of urinary tract calculi in children.

Renal stone disease remains a significant health problem in the adult population, with the incidence of urolithiasis estimated to be as high as 12%. The true incidence in childhood is not known, but a frequency of two children per million UK population per annum has been suggested. Understanding the factors involved in urinary stone formation and the appropriate investigations for a child presenting with signs and symptoms of renal stone disease, will allow for earlier recognition of the problem and may assist in the prevention of recurrent stone formation. The term “nephrocalcinosis” implies an increase in calcium content in the kidney, and is distinct from urolithiasis (stone in the urinary tract), although the two conditions may coexist. Nephrocalcinosis occurs less frequently than urolithiasis and may be focal, occurring in an area of previously damaged parenchyma, or generalised, usually as a result of an underlying metabolic disorder. The incidence and composition of renal stones diVers significantly with regard to geographic region. In European children infection related stones predominate. These stones are often located in the upper urinary tract, are composed of struvite (magnesium ammonium calcium phosphate), and are frequently related to proteus urinary tract infection. Hypercalciuria is the most common metabolic cause of stones in Western children. No diagnosis is determined in a quarter of cases. If more detailed investigations are undertaken it is possible that the number of “idiopathic” cases will decrease. The aim of this paper is to increase awareness of the importance of urolithiasis in children and to suggest an outline of investigations that will assist the physician in elucidating any underlying disorder.