Dysplastic kidneys in children - do they grow?

Dysplastic kidneys (DK) are a common cause of chronic kidney disease (CKD). Little is known about their growth or how their sonographic appearance changes. This study aimed to test the hypothesis that DK gain little length, and to identify radiologic trends predictive of CKD.

Ultrasound scans of children with DK born in 1980-2005 and referred to a single tertiary centre were analysed by a pediatric radiologist. Renal lengths were plotted on standard nomograms and the degree of dysplastic appearance noted. Factors related to DK - bladder outlet obstruction, vesico-ureteric reflux and renal impairment - were noted.

Fifty-three children were studied (83 kidneys), of whom 41 were boys; 289 scans were analysed. In 33 children there was associated bladder outlet obstruction or vesico-ureteric reflux. Forty-four DK were noted to fall off their renal length 'centile'. This correlated well with the development of CKD and is statistically significant. Deterioration occurred in 53% of DK; primarily progressive reduction in corticomedullary differentiation. This also correlated well with development of CKD.

More than half of the DK showed poor growth velocity. This, together with the degree of sonographic abnormality, carries a high predictive value for development of CKD. We recommend diligent serial sonography to follow renal growth and dysplastic appearance in children with DK.