Background: Idiopathic nephritic syndrome (INS) is one of the chronic illnesses in children. Therefore, clinical and laboratory factors that influence the clinical course of this disease are very important. Among these factors, low birthweight due to reduction of the number of congenital nephrons and subsequent glomerular hyperfiltration has been postulated as an important factor. This study was conducted to evaluate the clinical course of INS in patients with lowbirth weight in comparison to patients with normal birth weight.

Materials and Methods: In this descriptive-analytic study, 170 children with INS were selected from hospitals in Kermanshah, Urmia, Hamedan, Qazvin, and Ahvaz and divided into two groups of low birth weight (<2500gr) and normal birth weight (>2500gr). Then, the clinical course of these patients was evaluated by reviewing their medical records.

Results: Of the 170 patients, 22 had low birth weight and 148 had normal birthweight. Statistical analysis revealed no correlation between low birth weight and INS course except for age of presentation (P=0.014).

Conclusion: According to the results of this study, there is not any correlation between body birth weight and the clinical course of INS except for age of presentation.