Background: Children with nephrotic syndrome (NS) face increased infection risk due to immune dysregulation and immunosuppressive therapy. Pneumonia is a major cause of morbidity, but region-specific data from Iran are limited. This study aimed to determine the prevalence and associated factors of pneumonia among hospitalized children with NS in Urmia, Iran.

Methods: A retrospective record-based study was conducted at educational therapeutic hospitals in Urmia, including children aged 4–11 years with confirmed NS hospitalized between January 2020 and December 2024. Pneumonia was defined using WHO chest radiograph criteria. Multivariable logistic regression identified factors independently associated with pneumonia.

Results: Among 206 included children (median age 7.2 years, 57.3% male), the overall prevalence of radiologically confirmed pneumonia was 20.4% (95% CI: 15.1–26.6%). Community-acquired pneumonia accounted for 73.8% of cases, and nosocomial pneumonia for 26.2%. Prevalence was significantly higher in children aged 4–7 years versus 8–11 years (26.8% vs. 12.8%, p=0.012) and in steroid-resistant versus steroid-sensitive NS (34.0% vs. 16.0%, p=0.006). On multivariable analysis, younger age (aOR per 1-year increase: 0.76, 95% CI: 0.63–0.93, p=0.006) and higher relapse frequency (aOR per additional relapse: 1.42, 95% CI: 1.12–1.81, p=0.004) remained independently associated with pneumonia. Pneumococcal and influenza vaccination rates were low (29.6% and 23.3%, respectively).

Conclusions: Pneumonia affects one in five hospitalized children with NS in Urmia. Younger age and frequent relapses are independent risk factors. Suboptimal vaccination coverage represents a modifiable target for prevention. Clinicians should maintain low threshold for pneumonia diagnosis and prioritize immunization