Background <p>IgA nephropathy (IgAN) is the most common primary glomerulonephritis worldwide and a leading cause of end-stage renal disease. Renal histopathology represents a key intermediate phenotype linking clinical features and long-term renal outcomes. This study aimed to develop and validate a nomogram to estimate the likelihood of higher renal histopathological burden in patients with IgAN based on routinely available clinical variables.</p> Methods <p>This was a retrospective study including patients with primary IgAN confirmed by renal biopsy. Clinical and histopathological data at the time of biopsy were collected. Least absolute shrinkage and selection operator (LASSO) regression followed by multivariable logistic regression was used to identify factors associated with higher histopathological burden. A nomogram was constructed, and its performance was evaluated using calibration plots, receiver operating characteristic (ROC) curves with area under the curve (AUC), and Harrell’s concordance index (C-index).</p> Results <p>A total of 594 patients were included in the analysis. Age, mean arterial pressure, hemoglobin, estimated glomerular filtration rate, and proteinuria were identified as factors independently associated with higher histopathological burden and were incorporated into the final nomogram. The nomogram demonstrated acceptable discrimination, with C-indices of 0.702 (95% CI 0.643–0.761) in the development cohort and 0.732 (95% CI 0.647–0.817) in the validation cohort, along with good calibration.</p> Conclusion <p>A nomogram based on routinely available clinical variables was developed to estimate the likelihood of higher renal histopathological burden in patients with IgAN. This estimation model may provide complementary information for pathological assessment in clinical settings where renal biopsy data are limited.</p>