Widespread kidney anomalies in children with Down syndrome.

BACKGROUND: Rare autopsy studies have described smaller kidneys as well as urinary tract anomalies in Down syndrome. This observation has never been investigated in vivo and little is known about the possible consequences upon kidney function. Here we wish to confirm whether children with Down syndrome have smaller kidneys and to evaluate their kidney function in vivo.

METHODS: This retrospective cohort study enrolled 49 children with Down syndrome, as well as 49 age- and sex-matched controls at the Queen Fabiola Children's University Hospital in Brussels, Belgium. Doppler and kidney ultrasonography, spot urine albumin to creatinine ratio, estimated glomerular filtration rate (eGFR), and anthropometric data were recorded.

RESULTS: Kidney size in children with Down syndrome was smaller than age- and sex-matched controls in terms of length (p < 0.001) and volume (p < 0.001). Kidney function based on eGFR was also decreased in Down syndrome compared to historical normal. Twenty-one of the children with Down syndrome (42%) had eGFR < 90 mL/min/1.73 m2 , with 5 of these (10%) having an eGFR < 75 mL/min/1.73 m2 . In addition, 7 of the children with Down syndrome (14%) had anomalies of the kidney and/or urinary tract that had previously been undiagnosed.

CONCLUSIONS: Children with Down syndrome have significantly smaller kidneys than age-matched controls as well as evidence of decreased kidney function. These findings, in addition to well-noted increased kidney and urologic anomalies, highlight the need for universal anatomical and functional assessment of all individuals with Down syndrome. A higher resolution version of the Graphical abstract is available as Supplementary information.