Congenital solitary kidney size at birth could predict reduced eGFR levels later in life

Objectives: To evaluate the impact of congenital solitary functioning kidney (CSFK) length, measured early in life, on the eGFR levels during the follow-up. Study design: We retrospectively selected 162 CSFK patients undergoing, within 60 days of life, renal length (RL) measurement by ultrasound. We divided the population in:Group 1 = RL ≥ 2 standard deviation score (SDS).Group 2 = RL < 2 SDS and showing RL ≥ 2 SDS during the follow-up.Group 3 = RL < 2 SDS and showing RL < 2 SDS during the follow-up. Primary outcome: development of eGFR below the range of normality. Results: The median follow-up period of the overall population was 6.2 years (range 2–21.5 years). The cumulative proportion of patients free of primary outcome at 15 years of age was 96.4% in group 1, 64.6% in group 2, and 45.6% in group 3 (p = 0.03). The RL > 2 SDS within 60 days of life was a significant protective factor (hazard ratio = 0.13; 95% C.I. 0.02–0.97) against development of primary outcome. Conclusion: RL ≥ 2 SDS within 60 days of life could identify a population of CSFK with reduced risk of presenting reduced eGFR levels later in life.