Are children with congenital solitary kidney at risk for lifelong complications? A lack of prediction demands caution.

Congenital solitary functioning kidney (CSFK), which develops during embryo or fetal life, means having either one anatomical/functional kidney or two kidneys, one of which does not function. Similar anomalies have been seen in every other organ system and involve a large percentage of newborns. Still, prediction of long-term renal morbidity in congenital functioning solitary kidney is complicated by the great variability of renal and extrarenal phenotypes. Classification of different solitary renal types, whether or not a syndrome, may help to predict the possible evolution of complications; this may be hindered, however, by the gene-environment role during kidney development. Since the risk of renal failure in children with CSFK depends on several variables, it is always advisable to have a precise clinical description at diagnosis. This condition often requires long-term follow-up into adulthood.