biostudies-literatureWang XNational Natural Science Foundation of China100860https://www.ebi.ac.uk/biostudies/studies/S-EPMC12933437biostudies-literatureUnknown81<h4>Background</h4>A diagnostic nomogram for predicting tubulointerstitial lesions (T1/2) in IgA Nephropathy (IgAN), developed in Guangzhou (GZ) using estimated Glomerular Filtration Rate (eGFR) and Urinary Protein Excretion (UPE), demonstrated high accuracy (AUC = 0.92) but lacked external validation.<h4>Methods</h4>The authors externally validated the nomogram in an independent cohort from Kunming (KM, n = 387; median altitude: 1,891 m), including a high-altitude subgroup (> 2,000 m, n = 155). Model performance was evaluated using Receiver Operating Characteristic (ROC) curves, calibration plots, and Decision Curve Analysis (DCA). Both creatinine-based eGFR (eGFRcr) and Creatinine-Cystatin C-based eGFR (eGFRcr-cys), each combined with UPE, were assessed.<h4>Results</h4>The nomogram achieClinics (Sao Paulo, Brazil)External validation of a nomogram for predicting tubulointerstitial lesions in IgA nephropathy: a cross-regional study in China.PMC1293343782460150Yang MDeng QXu JZhao YSong LSun LWang QPu LWang XShen YMeng HLiu FXu YYu YfalseExternal validation of a nomogram for predicting tubulointerstitial lesions in IgA nephropathy: a cross-regional study in China.<h4>Background</h4>A diagnostic nomogram for predicting tubulointerstitial lesions (T1/2) in IgA Nephropathy (IgAN), developed in Guangzhou (GZ) using estimated Glomerular Filtration Rate (eGFR) and Urinary Protein Excretion (UPE), demonstrated high accuracy (AUC = 0.92) but lacked external validation.<h4>Methods</h4>The authors externally validated the nomogram in an independent cohort from Kunming (KM, n = 387; median altitude: 1,891 m), including a high-altitude subgroup (> 2,000 m, n = 155). Model performance was evaluated using Receiver Operating Characteristic (ROC) curves, calibration plots, and Decision Curve Analysis (DCA). Both creatinine-based eGFR (eGFRcr) and Creatinine-Cystatin C-based eGFR (eGFRcr-cys), each combined with UPE, were assessed.<h4>Results</h4>The nomogram achie2026-01-01T00:00:00Z2026 Feb2026-07-16T20:44:09.087Z2026-07-10T03:11:03.531ZS-EPMC129334374172005510.1016/j.clinsp.2026.100860