Trajectory of Estimated Glomerular Filtration Rate Predicts Renal Injury in Children with Multicystic Dysplastic Kidney.

Background/aims: Children with a solitary functioning kidney have a risk of renal injury caused by hyperfiltration. Timely intervention with renin-angiotensin inhibitors may be beneficial. We examined whether trajectory of estimated glomerular filtration rate (eGFR) would predict renal injury, defined as microalbuminuria/proteinuria, hypertension, and/or a decline in eGFR.

Methods: Seventeen patients (male 7, female 10) with multicystic dysplastic kidney (MCDK; median age 13 years, range 6-19 years) followed in our clinic were examined retrospectively. An eGFR decline was defined as a fall to < 90 mL/min/1.73 m2 or a decline of > 5 mL/min/1.73 m2/year for those with baseline eGFR of ≥90 or < 90 mL/min/1.73 m2 respectively.

Results: Nine patients had renal injury at the time of investigation. Compared with 8 patients without renal injury, those with renal injury tended to be older (14.7 ± 4.2 vs. 11.4 ± 4.6 years) and the birth weight was smaller (2,538 ± 281 vs. 2,966 ± 361 g, p < 0.05). The frequency of contralateral congenital anomaly of kidney and urinary tract (cyst, hydronephrosis, or vesicoureteral reflux) were not different. The trajectory of eGFR in those without renal injury was either an increase (n = 3) or unidentifiable (n = 5), whereas that in the renal injury group was exclusively an increase followed by decline (p < 0.05). The average age of the onset of eGFR decline was 9.4 ± 4.2 years and that of the start of renal injury (albuminuria/proteinuria 5, eGFR decline 4, hypertension 1) was 12.5 ± 4.2 years.

Conclusion: All the children with MCDK who developed renal injury had eGFR trajectory of increase followed by decline. Renal injury followed the peak eGFR by 3 years on average. This observation is in agreement with the hyperfiltration theory and underscores the importance of following eGFR trajectory closely.