Renal injury common in children with a solitary functioning kidney
MedWire News: Nearly a third of all children with a solitary functioning kidney (SFK) have hypertension, albuminuria, or use renoprotective medication at a young age, study findings indicate.
Furthermore, these three markers of renal injury occur regardless of the origin of the SFK (congenital vs secondary), but children with an SFK and ipsilateral congenital anomalies of the kidney and urinary tract (CAKUT) have more pronounced renal injury than those who have an SFK without additional renal tract malformations, report Joanna van Wijk (VU University Medical Centre, Amsterdam, The Netherlands) and colleagues.
Animal studies have led researchers to hypothesize that this type of renal injury is caused by glomerular hyperfiltration that follows renal mass reduction, although this theory remains unproven in humans, explain the researchers.
"By definition, a SFK from childhood onwards implies renal mass reduction for a longer period of time, suggesting that children with a SFK have an increased risk for developing hypertension, albuminuria, and chronic kidney disease," they add.
To investigate whether this is the case, van Wijk and team retrospectively reviewed data for 206 children participating in the KIMONO study (KIdney of MONofunctional Origin). The children were divided into those with primary (congenital) SFK (n=116) and those with secondary SFK (n=90). In addition, ipsilateral CAKUT were identified in 30 (26%) children with a primary SFK and 27 (30%) children with a secondary SFK.
Renal injury, defined as the presence of hypertension and/or albuminuria and/or the use of renoprotective medication, was present in 32% of all children with a SFK, at a mean age of 9.5 years.
The rate of renal injury did not vary between the children with primary and secondary SKF, at 32% and 31%, respectively, but was significantly higher among children with CAKUT compared with those without it, at 48.3% versus 24.6%.
The researchers also created a longitudinal model to estimate changes in blood pressure, albuminuria, and estimated glomerular filtration rate (eGFR) over the course of childhood in the participants.
The model showed that blood pressure progressed as normal in all children, irrespective of whether they had primary or secondary SFK, but the glomerular filtration rate was in the microalbuminuric range in children with primary SFK at 18 years of age.
Furthermore, eGFR increased in both groups from infancy until the age of 9 years for primary SFK and 11 years for secondary SFK, but then decreased from the beginning of puberty onwards into late adolescence.
Of note, children with ipsilateral CAKUT had a significantly lower eGFR over childhood and reached maximum eGFR at an earlier age than children without CAKUT.
The model suggested that this trend "persists over adulthood and therefore might lead to chronic kidney disease in later life," the researchers remark.
"Our results emphasize that having an SFK from childhood is not a harmless malformation but necessitates clinical follow-up on a regular basis from childhood onwards," write van Wijk and co-authors in the journal Nephrology Dialysis Transplantation.
"Since all children in our study with an impaired eGFR also showed at least one other symptom of renal injury, we propose screening for renal injury in every child with an SFK by measurement of blood pressure and urine analysis on albumin," they conclude.
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By Laura Dean