Objective To evaluate the early warning value of combined detection of urinary neutrophil gelatinase-associated lipocalin (NGAL), urinary microalbumin and fecal calprotectin for IgA vasculitis with nephritis (IgAVN). Methods A total of 90 children with IgAV and 50 healthy children undergoing physical examination at Yichun People's Hospital from January 2024 to December 2025 were enrolled. Based on urinalysis at admission and at 3-month follow-up, IgAV cases were classified into a simple IgAV group (n=48) and an IgAVN group (n=42; abnormal urinalysis). The IgAVN group was further divided into a mild renal injury subgroup (n=25) and a moderate-to-severe renal injury subgroup (n=17). Pearson correlation analysis, multivariable logistic regression and receiver operating characteristic (ROC) curve analysis were used to assess the diagnostic and early warning value of each marker. Results Levels of urinary NGAL, urinary microalbumin and fecal calprotectin in the IgAVN group were significantly higher than those in the simple IgAV group and the control group (P<0.05). Children with moderate-to-severe renal injury had higher levels of all three markers than those with mild renal injury (P<0.05). Correlation analysis showed that all three markers were significantly positively correlated with the severity of renal injury (P<0.05). ROC analysis indicated that combined detection of the three markers provided significantly better early warning performance than any single marker (P<0.05). Conclusions Combined detection of urinary NGAL, urinary microalbumin and fecal calprotectin improves early warning for IgAVN in children, providing a reliable laboratory basis for early clinical intervention and better prognosis.