Low birth weight is a conditioning factor for podocyte alteration and steroid dependance in children with nephrotic syndrome

Background Low birth weight (LBW) is associated with reduced nephron endowment. Clinical-pathologic features of post adaptive focal segmental glomerulosclerosis (FSGS) have been observed in subjects with prematurity and very LBW. Methods We aimed to investigate the correlation between LBW and outcome in a cohort of 89 children with idiopathic nephrotic syndrome (NS) (2-12 years-old at onset, followed for > 3 years), of whom 21 with LBW (birth weight < 10th percentile for gestational age, gender, ethnicity, and maternal parity or birth weight < 2500 g). Results Children with NS and LBW were found to have FSGS more frequently than children with normal birth weight (NBW) [8/21 = 38% vs. 4/68 = 6%; odds ratio, OR 7.754 (95% confidence interval, CI 2.184-27.525); chi(2) = 9.817; p < 0.003]. Children with LBW and cortico-sensitive NS had a greater risk of cortico-dependence (CD) than those with NBW [10/13 = 76.9% vs. 28/63 = 44.4%, OR 4.744 (1.188-18.936); chi(2) = 4.158; p < 0.05]. Moreover, children with LBW and CDNS needed a greater dose of immunosuppressive drugs than those with NBW [OR 4 (1.153-13.877); chi(2) = 3.842; p = 0.05]. Conclusions LBW children developing NS had higher risk of FSGS and CD, and needed heavier immunosuppressive therapy than those with NBW. These data might suggest a conditioning role for hemodynamic and podocyte changes due to reduced nephron mass in LBW.